UFOpaedia - User contributions [en]

GEOSCAPE.EXE

2009-01-19T21:38:14Z

Wfames:

The "Geoscape" program that handles base management and aircraft, a.k.a. XCOM outside of tactical combat. [[TACTICAL.EXE]] handles combat.

'''NOTE:''' In the WinCE version, GEOSCAPE and TACTICAL are one executable, "UFO Defense.exe". Due to this confusion (what wiki pages place things on, when they're practically identical), currently GEOSCAPE, TACTICAL, and UFO Defense information appear here. (Unless and until someone wants to break everything up... then again, having highly related stuff in one place is a good thing.)

Also see [[Versions]].

= X-COM Complete Packages =

This entry is only a stub for the moment. We grognards on the wiki ask anyone who has bought one of the new packages to tell us things like:
#Who did you get it from - GamersGate, Steam, or elsewhere? (If it is found that they're both selling the exact same package, we'll say so here.)
#What version of X-COM UFO Defense is included? Probably the Win CE version (below), yes?
#Any trouble installing, or other considerations to keep in mind?
#Any problems versus what you expect from X-COM? (if you played it before, or have been reading this wiki, or whatever)
Et cetera. This info is intended to help those who might buy the packages in the future, and is also intended to tell us old hands what's in the package.

Once we get 3-5 mini-reviews, we'll remove these italicized comments, and collapse reviews into a more "wiki-like" overview. (We'll include a link to the time/version when you posted individual reviews.) So, newcomers who bought the Complete Package, please make a new "Review #(next #)" section below, with a summary review. And see the new [[Talk:GEOSCAPE.EXE#New Bundles]] section for more in-depth Q&A and comments.

If any of you have the ability to make comments on Steam or GamersGate that are tacked onto the new X-COM bundles, please post a comment letting people know about this wiki. '''www.UFOpaedia.org''', loud and proud. It's 1999. We're here to save Earth.

''Thanks, and welcome!''

'''wfames, elliotw2, or other new Complete Package folks - please put your comments under a heading like the one below - thanks!''' -[[User:MikeTheRed|MikeTheRed]] 03:51, 19 January 2009 (CST)

==Review #1 by wfames==

Everything seems fine except for psionics. Soldiers in both original X-Com and TFTD do not seem to gain any Psi Skill for either successful or unsuccessful mind control attempts. MC also never seems to work more than once in any given battle. Makes psionics practically useless. It's still a great game, even with that frustration, though.

= XCOM: UFO Defense (U.S. DOS) version 1.4 =
*Is 382,957 bytes long for the virgin 1.4 executable
*Has [[Alien_Stats|alien statistics]] starting at (non-offset) byte 379,729. There are 33 records of 39 bytes each. No alien names, though.
*If you have installed [[XcomUtil]], it may alter the length of GEOSCAPE. ''Does anybody have a modified version, so we can put the length here? --[[User:MikeTheRed|MikeTheRed]]''
** My XCOM Util GEOSCAPE size is 415,271 --[[User:Pi Masta|Pi Masta]]

= XCOM Windows Collector's Edition =
*Variously called the '''Win CE''' or '''Gold''' version on the wiki
*Is 495,616 bytes long
*Starting at byte 648, reads:
XCOM: UFO Defense Gold Edition
This awesome game was compiled on Sep 8 1999 at 08:57:11
Copyright - 1999 Hasbro Interactive/MicroProse Software
Party on dude.
*If you install XcomUtil, it separates your ''UFO Defense.exe'' into GEOSCAPE and TACTICAL executables. They are almost identical copies of ''UFO Defense.exe'', however they start at the right place when run. This allows the game to closely mimick the Dos version by having its main loop run in a batch file.
*Has [[Alien_Stats|alien statistics]] starting at (non-offset) byte 480,145 (75391x). There are 33 records of 39 bytes each. No alien names, though.
*Has tank & inbuilt alien weapon stats at byte 447,868 (6D57Cx, see below).
*Has the copy protection codes written in the manual starting at byte 475,176 (74028x) (despite the fact that the game stopped asking for these prior to the Windows port!).

= Vehicle Stats =

At offset 353,020 in X-COM 1.4 (DOS - modified by XCUtil), the vehicle statistics begin.

Each Vessel Statistic is two bytes and is 0 through 65,535 (in UGE format), and go in the following order:

Maximum Speed 
Acceleration 
Fuel 
Damage 

To help you find it in UGE, here are the various X-COM vessel section in UGE format:

Skyranger: 248 - 2 - 2 - 0 - 220 - 5 - 150 - 0 
Lightning: 28 - 12 - 8 - 0 - 30 - 0 - 32 - 3 
Avenger: 24 - 21 - 10 - 0 - 60 - 0 - 176 - 4 
Interceptor: 52 - 8 - 3 - 0 - 232 - 3 - 100 - 0 
Firestorm: 104 - 16 - 9 - 0 - 20 - 0 - 244 - 1 

A bit below the Firestorm statistics are the stats for various Alien Ships, I'll probably do them later.

At offset 380,668 the Tank Statistics begin.

= Armor Stats =

At offset 369,898 in the DOS version; the personal armor statistics begin.

The Statistics are in two byte format and go in the following order:

Front Armor 
Left Armor 
Right Armor 
Rear Armor 
Under Armor 

To help you find it in UGE, here are the various armor stats in UGE format:

Unarmored X-COM Personnel: 12 - 0 - 8 - 0 - 8 - 0 - 5 - 0 - 2 - 0 
Personal Armor: 50 - 0 - 40 - 0 - 40 - 0 - 30- 0 - 30 - 0 

So on, etc.

= Alien Stats =

This section is for the structure of the alien stats, as found in GEOSCAPE. For actual data and additional information, see the [[Alien_Stats|alien statistics]] page. Also see Zombie's excellent alien stats page at [http://www.strategycore.co.uk/xcom/pg/ufoalienstats StrategyCore]. ''(Have YOU made your StratCore and [http://www.xcomufo.com XCOMUFO] accounts yet?)''

Alien stats are found as 33 records of 39 bytes each, in all versions of X-COM. They are identical in all versions. This data actually represents the "core" alien stats; modifiers are used to determine the final stats relative to game difficulty level. (In most, but not all, cases, the core stats are the same as the Beginner level stats.)

Alien stats start in each version of X-COM at the following location. This is a byte ''count'', not an offset; with counts, the first byte in the file is byte 1:
Version Location
DOS 1.4 379,729 (GEOSCAPE.EXE)
WinCE Gold 480,145 (UFO Defense.exe)
Playstation 501,212
TFTD 486,930

Alien names are not actually found in Geoscape; it just has 33 strings of data... the alien each string applies to has been inferred by matching against aliens in the game.

The 39 bytes correspond to the following values. For the below, statements also apply to TFTD, since it's relevant to understanding the bytes:

'''0:''' Race - Corresponds to Unitref[000]

'''1:''' Rank - Corresponds to Unitref[042]

'''2:''' ''Unknown - Always 0'' - Corresponds to Unitref[011]

'''3:''' Can Fly - No Corresponding Unitref offset

'''4:''' TUs - Corresponds to Unitref[025]

'''5:''' Health - Corresponds to Unitref[026]

'''6:''' Energy - Corresponds to Unitref[027]

'''7:''' Reactions - Corresponds to Unitref[028]

'''8:''' Strength - Corresponds to Unitref[017]

'''9:''' Firing Accuracy - Corresponds to Unitref[023]

'''10:''' Throwing Accuracy - Corresponds to Unitref[024]

'''11:''' Melee Accuracy - Corresponds to Unitref[056]

'''12:''' Front Armor - Corresponds to Unitref[029]

'''13:''' Left Armor - Corresponds to Unitref[030]

'''14:''' Right Armor - Corresponds to Unitref[031]

'''15:''' Rear Armor - Corresponds to Unitref[032]

'''16:''' Under Armor - Corresponds to Unitref[033]

'''17:''' ''Unknown - Always 0'' - Corresponds to Unitref[034]

'''18:''' Energy Recharge - Corresponds to Unitref[035]

'''19:''' ''Unknown - Always 0'' - Corresponds to Unitref[036]

'''20:''' ''Unknown - Always 1'' No Corresponding Unitref offset

'''21:''' ''Unknown - Always 0'' - Corresponds to Unitref[046]

'''22:''' ''Unknown'' - Corresponds to Unitref[048] (see below)

'''23:''' ''Unknown'' - Corresponds to Unitref[052] (see below)

''NOTE: For additional important info on the last two bytes, see [[Talk:UNITREF.DAT]]. My notes below do not take that info into account. For the moment though I'm leaving it as is. I sure wish we could figure the bytes out, and get rid of all the conjecture! - [[User:MikeTheRed|MikeTheRed]] 08:05, 6 November 2006 (PST)''

These Unitref bytes ([48] and [52]) and now Geoscape Core values have long stumped us hardcore X-Commies. The two bytes always equal the same value for a given alien, including all aliens of the same race (the N's below). And, they're the same between Geoscape and Unitref. Clearly it must be important (or a goof!), but exactly what it is, who knows. Although this page is for X-COM, I've included TFTD in the hopes it helps folks - but it's been so long since I've played TFTD, I can't remember those units at all.

How's this for a thought?...
Dimension Byte(s)

X 22

Y 23

Z 24 (top when standing)
25 (top when kneeling)
26 (bottom)

Maybe they represent the "size in profile" ("width"), affecting likelihood to hit. A game could be tried with a target 20 squares away, set 22 and 23 alternately to 5 or 2 (or 1 or 0?), and see if it affects the successful shots percentage. 0 or even 1 might break the game, though.

Also, how do these values (2 to 5) correlate with the "pixel drawings" of units? I can't seem to find that info at the moment... aren't units and tiles defined as something like 16x16x[[Height|28]]? If so, then perhaps the values (2 to 5) are multiplied by 3 or something to get their final "width" for bullet interception?? --[[User:MikeTheRed|MikeTheRed]] 05:20, 17 September 2006 (PDT)

:I finally got the OSG (w00t!), and noticed the following: The section on weapon accuracy says (p. 221) that target size affects the chance to hit, and "the 'size' of each alien is listed along with all other alien statistics in Chapter 9". But the alien stats tables (p. 250 ff.) only lists Height as a possible 'size' stat, and the text write-ups don't otherwise address "target size" with any precision. This discrepancy - that Chapter 8 talks about '''size''', but Chapter 9 only has '''height''' - might (might!) mean there are more variables that determine target area size, but somehow they didn't make it to the alien stats tables.

:The description for Height (p. 249) does say, "Taller creatures are easier to hit than short ones are. An alien with a height of 40, for example, is twice as easy to hit as an alien with a height of 20." (Note: The tallest [[Height]] is actually 23. And also notice, Float is never mentioned.) This ''might'' mean only height affects this, or it could be read in a general way; other dimensions (X and Y in addition to Z) might also affect it.

:Somebody should do some firing accuracy tests while hacking these potential X & Y bytes! But I still don't know how the values for [22] & [23] compare to what X-COM considers tile width... we know the Height byte accurately reflects the full range of possible values (0 to 23), but I doubt 5 is the full (pixel?) width of a tile. This might mean it's not width, then (or maybe [22] & [23] are added, or they are individually multiplied by 3 or something??) If anyone who knows about tile width could say something, I'd appreciate it. --[[User:MikeTheRed|MikeTheRed]] 11:24, 1 October 2006 (PDT)

In any event, here's a summary of bytes [22] and [23], in the hopes we can figure it out. They're always identical for a given race, and [22] always equals [23].

'''X-COM TFTD'''

Value Alien N Value Alien N

2 Sectoid 6 2 Aquatoid 6
Bio-Drone 1
3 Celatid 1 Tentaculat 1
Chryssalid 1
Civilian 2 3 Calcinite 1
Ethereal 3 Civilian 2
Floater 6 Deep_One 1
Muton 3 Gill_Man 4
Snakeman 5 Tasoth 2

4 Cyberdisc 1 4 Coelacant 1
Hovertank 1 Displacer 1
Reaper 1 Hallucinoid 1
Sectopod 1 Lobster_Man 5
Tank 1 Triscene 1
Xarquid 1
5 Silacoid 1

'''24:''' Standing Height - Corresponds to Unitref[049]

'''25:''' Kneeling Height - Corresponds to Unitref[050]

'''26:''' Floating Height - Corresponds to Unitref[051]

'''27:''' [[Damage#Susceptible_to...|Damage Modifier]] Category - Corresponds to Unitref[055]

This field is simply a look-up table, or more directly, a way to categorize the units into similar groups. The actual modifiers are listed elsewhere in the executable. A value of 1 indicates the second DM category, a value of 4 indicates the 5th, etc. The values of 2 and 3 are not seen in the alien stats as they refer to X-COM soldier armor info. I'm not sure about 13 as the Zombie's stats haven't been found yet, but there is a category in the DM's for it.

'''Category''' '''Unit Type(s)'''
'''0''' Not for units, but is used for Terrain and Items
'''1''' Civilian, Sectoid, Celatid, Floater
'''2''' Personal Armor
'''3''' Power Suit, Flying Suit
'''4''' Tanks, Hovertanks
'''5''' Snakemen
'''6''' Ethereal
'''7''' Muton
'''8''' Silacoid
'''9''' Chryssalid
'''10''' Reaper
'''11''' Sectopod
'''12''' Cyberdisc
'''13''' Zombie

'''28:''' Psi Skill - Corresponds to Unitref[037]

'''29:''' Psi Strength - Corresponds to Unitref[057]

'''30:''' Bravery (encoded) - Corresponds to Unitref[059]

'''31:''' Motion scanner size - Corresponds to Unitref[061]

'''32:''' ''1 for Cyberdisc, 0 for all others including TFTD... isn't "Explodes"; the TFTD Bio-Drone also explodes...'' - Corresponds to Unitref[071]

I edited the Cyberdisc's field to 0 and checked to see if it exploded. It still did. Obviously this field is for something else. I'll work on this some more. --[[User:Zombie|Zombie]] 20:15, 15 September 2006 (PDT)

'''33:''' ''Unknown - Always 0'' No Corresponding Unitref offset

'''34:''' Corpse type - Corresponds to Unitref[038]

'''35:''' Big unit (2x2) No Corresponding Unitref offset

'''36:''' Victory point score - Corresponds to Unitref[039]

'''37:''' Aggression - Corresponds to Unitref[044]

'''38:''' Intelligence - Corresponds to Unitref[073]

''This data was just put together working heavily with Zombie and his great SC [http://www.strategycore.co.uk/xcom/pg/ufoalienstats alien stats] page.

= Country Labels =
Starting at offset 396480 (hex: 0x60CC0) are the records that contain the location of the labels for the country names on the world. In order they are X, Y, and English.dat index all signed short integers (6 bytes for each record). X should never be negative but between 0 and 2880, Y should be between -720 and 720 (See [[WORLD.DAT]]). The English.dat file, despite all other array indexes appears to start at 1 and not 0, thus a value of 611 in here represents index 610 in a zero based English.dat array. (It stands to reason that these work for the other language files as well)

= File Templates =
There appears to be 'templates' of some of the [[Saved Game Files|game files]] stored within this executable. Makes sense as initially no saved game files are present when installed. Here is a list of known positions and the corresponding file. Offsets are from DOS Version of the game patched with XComUtil
{| {{StdDescTable}}
|- {{StdDescTable_Heading}}
! Offset (Hex) !! Offset (Dec) !! Length (Bytes) !! File
|-
| 5AB28 || 371496 || 2112|| [[RESEARCH.DAT]]
|-
| 5B5E0 || 374240 || 272|| [[FACIL.DAT]]
|-
| 5B6F0 || 374512 || 1820|| [[PURCHASE.DAT]]
|-
| 5D894 || 383124 || 576 || [[DIPLOM.DAT]]
|-
| 5E48C || 386188 || 1392|| [[UP.DAT]]
|-
| 5EB90 || 387984 || 84|| [[ACTS.DAT]]
|-
| 5FAC0 || 391872 || 2336|| [[BASE.DAT]]
|-
| 5FBB8 || 392120 || 5200|| [[CRAFT.DAT]]
|}

Possibly these are in-game data structures used to hold the current in-memory state, between game saves?

= Detection Ranges =

Detection ranges are hard coded into the executable at the following locations (Win CE / Gold edition):

{| cellspacing="0" border="1"
!Platform
!Address
!Data bytes
!Hex
!Range
!nm
|-
|Aircraft||591EA||C8 00||x00C8||200||600
|-
|Hyperwave||59237||20 03||x0328||800||2400
|-
|Lg Radar||5926D||EE 02||x02EE||750||2250
|-
|Sm Radar||59278||F4 01||x01F4||500||1500
|}

Patching "88 13" to these locations = x1388 = 5000 range units = 15,000 nm pretty much gives that platform visibility over the whole world. Of course Small Radar still only has a 10% detection chance per half hour.

= Battlescape Terrain List =

In the UFO CE executable, offset 476156 (743FCx) marks the beginning of the [[WORLD.DAT]] terrain to battlescape terrain conversion list. 13 double byte values.

02 00 01 00 01 00 01 00 01 00 07 00 02 00 06 00 06 00 08 00 00 00 02 00 08 00

For example, a mission initiated in a GeoScape polygon of type 5 will be performed in battlescape terrain type 7 (mountains).

Note that jungle (type 00) missions in the north will end up as forest missions, and forest (type 02) missions in the south will end up as jungle missions. See offset 10 in [[GEODATA.DAT]] for the full battlescape terrain list.

= See Also =
* [[TACTICAL.EXE]] - Sister executable used for Turn based strategy (merged with geoscape.exe in WinCE edition)
* [[UNITREF.DAT]] - Stats on current units (both XCOM and Alien) in play
* [[Saved Game Files]]

[[Category:Game Files]]

User:Wfames

2009-01-19T07:40:23Z

Wfames: New page: Hello. I'm a new user and a new player. I picked up x-com off of Steam in 2008, and have been happily playing it more or less every free moment, though there aren't many as a physics maj...

Hello. I'm a new user and a new player. I picked up x-com off of Steam in 2008, and have been happily playing it more or less every free moment, though there aren't many as a physics major applying to grad school.

Talk:Psionics

2009-01-19T07:38:52Z

Wfames:

Just had a thought on the formula!

What if the "Psionic Combat Strength" formula was a''' ' + ' '''rather than a''' ' * ' '''?

It would mean the example Soldier would have a PCS of 111, rather than 1520, and the defending Muton would have:

Panic Chance = 76%
MC Chance = 56%

These numbers seem more reasonable, don't you think?

--[[User:Danial|Danial]] 15:32, 19 Nov 2005 (PST)
----
Right, it sounds '''much''' more reasonable now. My actual results were 1192 successes out of 2420 tries = 49.26% success rate. The MCer was right next to MC victim, and we know distance introduces ''some'' kind of decrease to base chance. That's the good news. The bad news is that I also tested psi str 95, skill 44 (and some higher skill levels) and never failed to MC ''once'' with these better MCers. Using your revision, a psi str 95, skill 44 guy should have had a success rate of 84% vs. a beginner Muton soldier (psi str 25, skill 0), not 100%. My higher-skill guys were also right next to their MC victims. So, to me the first example makes sense relative to your idea (fits base chance, plus a little distance adds a little more), but the second example counters it.

Still, it sounds WAY better than 1500% :)

I sure wish psi testing wasn't so labor intensive. I got those 2400 counts doing all that experience testing... not interested in doing it again, just for psi equations. At least not at the moment. :P ---[[User:MikeTheRed|MikeTheRed]] 21:12, 23 Nov 2005 (PST)
----
Question: why is the Sectopod's psionic resistance listed as N/A? I've mind-controlled sectopods (or at least one square of a sectopod) on many occasions. I usually have it shoot itself, since it can target one of its other, non-MC'ed squares. From my anecdotal experience, their psi resistance seems somewhat high. --[[User:Papa Legba|Papa Legba]] 14:19, 2 February 2006 (PST)
----
Answer: If you look on the alien summaries in the wiki they all have a PSI resistance listed, except the Sectopod. Since it's not listed anyplace I put N/A. Feel free to put it where it belongs in the list if you have enough experience to feel comfortable ranking it. --[[User:Darksun|Darksun]]
----
Darksun, I took the liberty of signing your name for you, and making a separator line. Why not say a word about yourself under [[User:Darksun]] and also, use four dashes (----) to demarcate entries. For more on the basics of wiki'ing, see NKF's "Community Portal" at the bottom of the homepage. Past all that - welcome, fellow XCOMMIE! We were all wiki noobs once. But not everybody loves XCOM. You must. Welcome aboard!

Proceeding right along to flagellating, laugh - Where are you folks talking about Sectopod psi resistance being "N/A"? I see their Psi Strength as 100, and their Psi Skill as 0 at Beginner; Psi Strenth 116 and Skill still 0 at Superhuman. In this respect, they match Cyberdisks. What do you folks mean by Psi "resistance"? Do you know the math behind the psi equations? I haven't been able to figure it out. But the stats I just listed are ones hacked out of the game... Zombie is going to present a full precis' some time soon.

Great speaking at ya ... keep on contributing, Darksun!! --[[User:MikeTheRed|MikeTheRed]]

== Alien psionic resistance ==

I haven't tried mind-controlling Cyberdiscs much, but if, as I've read elsewhere, both Sectopods and Cyberdiscs have have a Psi Strength of 100, they should probably both be classed "extremely high".
--[[User:Ethereal Cereal|Ethereal Cereal]] 10:30, 4 May 2006 (PDT)

== Psionic testing ==

I started doing some testing to figure out the psionics formula.

Initial finding: ''distance'' takes the hypotenuse into account. I'm not sure if the actual Pythagorean formula is used, but I can say this much: an Ethereal was able to panic a moderately-psi-weak soldier at 30 squares along the horizontal but not at 30 squares along the diagonal.

Second finding: the difference in "difficulty" between MC and panic is definitely 20 points (although that may not be percent). A soldier with 97 Psi strength, 0 Psi skill standing adjacent to an Ethereal Leader (60 str/45 skill) could not be panicked at all, but 96 Psi str could (often). The same soldier with 77 Psi str couldn't be mind-controlled, but could at 76 Psi str. ''With further testing, I see that 60/45 vs. 97 should succeed occasionally; I might retest this for greater precision, although the +20 still seems to hold.''

Third finding: A soldier with 99 Psi str/0 skill could ''just barely'' be panicked by an adjacent Ethereal with 63/45. I couldn't count how often the Ethereal succeeded, but it was something like 1%-2% of the time. The same soldier was panicked just as infrequently by an Ethereal with 45/63 (str & skill reversed), and much more often by an Ethereal with 54/54. This pretty strongly suggests the attack portion of the formula involves psi str & skill multiplied together.

Data points collected so far:
*Ethereal, 63/45, just barely panicked soldier, 99/0
*Ethereal 40/40 just barely panicked soldier 75/0
*Ethereal 27/27 (multiplied together = 729) just barely panicked soldier 57/0
*Ethereal 10/73 (multiplied = 730) just barely panicked soldier 57/0
**''this confirms that attacking is based on str*skill
*Ethereal 18/18 just barely panicked soldier 49/0
*Ethereal 1/1 just barely panicked soldier 43/0
*Ethereal 1/1 just barely panicked soldier 1/210
**''this confirms Psi skill / 5 is used in calculating defense; 1 + (210/5) = 43''

I also tested Ethereal 0/1 (no psi str, 1 pt. skill); it still attacked, but did not attack at 0 pts. skill no matter how high psi str was (no surprise there, otherwise all units would do psi attacks).

I ran the points through a curve-fitting program and got a nice and simple answer:

attack strength = psi str * psi skill '''/ 50'''
defense strength = psi str + (psi skill / 5)

Panic Attack chance = 44% + attack strength - defense strength
Mind Control Attack chance = 24% + attack strength - defense strength

The formula has held up under limited further testing; I'm satisfied it's correct. I invite others to test it more than I have.

The impact of distance has yet to be tested, but it should be easy to figure out now.

--[[User:Ethereal Cereal|Ethereal Cereal]] 22:03, 26 May 2006 (PDT)

----

There is a reasonable approximation to the Pythagorean formula (in the plane) that could have been used, that doesn't require loops or floating-point math:

max( | Δx | , | Δy | ) + ½min( | Δx | , | Δy | )

where Δ_ := _2 - _1.

It overestimates slightly. I haven't thought through how this would generalize to 3D. [Yanked from Moria, Angband, and variants...think it's too basic to copyright, though.]

One way to test whether the distance estimator is no greater than true Pythagorean formula by working out the greatest distance (pure x or pure y) that MC/Panic is not 0%, then testing on a diagonal with a "computed same". An integer-math overestimator (like the above) would by 0%.

Muliple of 5 allows replacing the diagonal with a suitably scaled 3-4-5 triangle...should work as well for testing.

--[[User:Zaimoni|Zaimoni]] 2:38PM, 26 May 2006 (CDT)

----

Wow... good approach to teasing this out, Ethereal!

Am I doing this right? I plugged in numbers for Muton, 25/0, Me 95/44, and got 83% MC Base Chance... But in much repeated testing (when learning about experience counters) it seemed quite solid that I was MC'ing him about half the time. Say 45-55% of the time. This was when right next to each other. Is 83% right for your equations?

Zaimoni, re: your equation, see [[Explosions#Distance_from_Ground_Zero]]. XCOM seems to use a fairly simple approach that doesn't involve Pythagoras per se. Since it's based on a very old engine, much of its stuff is integer based. Cool deal on the deltas and other wiki symbols - I wish I knew about them sooner! Actually I know where wiki symbol tables are... just didn't bother to look up so many symbols. :P

Nobody has tackled 3D distance yet, but I may soon, in studying illumination.

Once the equations are well known (maybe they are already), I imagine some cool 3D topographical graphs of the various factors (skill and strength, you vs. enemy) could be made. Do either of you have surface graph s/w at hand? All I've got at the moment is Excel. :(

Great work! Also thanks for cleaning up the page in general, Eth.

---[[User:MikeTheRed|MikeTheRed]] 22:24, 2 June 2006 (PDT)

----

I suspect you've misremembered the details of your tests. The 49.26% success rate out of 2400 trials that you quote above would have been for your 95/16 soldier doing panics, not MCs: 44 + [95*16/50 = 30.4] - 25 = 49.4%, almost exactly the same as your 49.26%. A 95/44 doing panics would always succeed: 102.6%. A 95/44 doing MCs would succeed 82.6% of the time.

--[[User:Ethereal Cereal|Ethereal Cereal]] 11:06, 3 June 2006 (PDT)

----

Ah, there's that data. Thanks for reminding me. I can't remember what I put in which discussions and was going to dig it out of my db.

No, it was MCs. Indeed I relied on the lack of seeing an enemy, if I got moving too fast and couldn't remember if I successfully MC'd. Attention starts to wander with such highly repetitive testing. This was before I realized the following...

Anyone doing repetitive psi testing can readily and accurately get the number of positive results from the [[UNITREF.DAT]] Psi byte [84] if you work it right. Note the turn you start psi attempts. Then do exactly 2 or 3 psi Attempts each turn, as your TUs allow. Then note the turn you stop and get the delta. Turns x Attempts/Turn = Attempts. A failed psi attempt adds 1 to [84] and a successful attempt adds 3, so the number of successes is: ([84]-Attempts)/2. Be careful during testing marathons because the byte wraps around at 255 (=85 straight successes, or 28.3 turns at 3 successful attempts per turn). Then it starts counting again so actually even this can be dealt with by adding 255 if you're on top of it. If anybody wants an applet that shows Unitref experience values on the fly, let me know. It's great for building experience. Right now it's embedded within my mdb though... I'd have to tease it out.

I'm using XCOM DOS which I once ran XcomUtil on, if that matters.

Hmm.

---[[User:MikeTheRed|MikeTheRed]] 12:21, 3 June 2006 (PDT)

----

Distance...ok, no reason for the game to use multiple 2-d distance formulæ.

I have software set up to render 3D graphs. Is there anything on the site that jumps out as "would like to see first"? I'd rather wait until the psi formulæ are calibrated first before graphing those.

Ethereal: What I see posted is test data for ethereal MC human. Do you have test data for human MC ethereal as well? [That would test whether the game calculations are symmetrical.]

---[[User:Zaimoni|Zaimoni]] 2:37, 3 June 2006 (EDT)

----

It ''is'' possible X-COM units get a different formula from aliens -- I only tested an alien doing psi, as it was more automated -- the thing would psi without my having to control it.

I'm not not volunteering to test x-com units for the time being -- it's a bit more laborious -- but if I ''had'' to test it, I'd do a small number of trials of 35/16, 50/51, and 100/51 soldiers trying to MC (not panic) an adjacent Muton, which should succeed 10.2%, 50% and 101% of the time.

Feel free to test it before I do. ;-P

Oh, and nice work on the flares, Mike.

--[[User:Ethereal Cereal|Ethereal Cereal]] 12:50, 3 June 2006 (PDT)

----

Sounds cool, Zaimoni... As for "like to see",

Once my troops have psi ability, I try to get 90+ psi strength guys. Then the question becomes "at psi str 90, at what psi skill point are most/all aliens certain to be MC'ed?" In my experience, it's somewhere around skill 40-60... Anything that might show this, or show how you fare relative to aliens at, say, STR 90, is something I've always wanted. However it might be done. In one sense you could simply plug the "worst" psi alien (Ethereal CDR?) into Eth's equations to get the final answer. But it'd be good to see the lay of the land.

If you make the simplifying assumption that many of your targets are psi skill 0, there's one less variable. Additional graphs can be done later just for the psi-capable aliens... first things first though...

Taking the above into consideration, then, XCOM Psi Skill (Str=90) vs. Alien Psi Strength (Skill=0) vs. Success rate is one 3D graph that could be made. If you can do a 4th dimension as color, you could replace the Success rate axis with XCOM Psi Str, then have color indicate success rate, from primary red for "no way" through yellow for "sometimes" to primary green for "always". Or something like that. It'd also be nice but not critical to have annotations for where various aliens lie along their dimension. I can supply this info if you want. Which reminds me: Eth, Zombie and others found some errors in Aztec's table (which came from the OSG). Just a few percent of them, but they're definitely there (I can't remember where). I've hacked alien stats straight out of GEOSCAPE... see the alien stats page. I believe Zombie has found these to be correct, but he has not yet given the final word.

Zai, as far as I'm concerned, you can model using EC's equation already, if you have the time... I'm sure his equations are very close, if not spot on, and even if not, it may show key places to test and otherwise support further testing. E.g., both aliens and XCOM can readily have their relevant values hacked to test for boundary conditions of 0% and 100% success. Plus once it's set up it shouldn't be hard to tweak the equation and voila, the graphs update. But if you don't have the time - eh, it's all volunteer work anyway.

Eth, I suppose it's possible aliens vs. humans is different. They are known to have some differences in functionality, such as night vision. I don't know if I'll be able to test, but it definitely intrigues me. BTW I said somewhere else that I was looking into automating the XCOM interface in order to do psi testing. I have concluded that I can't do it. At least not the way I was hoping to. Oh well. Still, my belated realization that one can use Unitref[84] to count psi successes is a real boon to repetitive testing. So we'll see. Thanks for suggestions on what to test if I do. By the way, did I do that 83% correct? I just want to make sure I'm doing the math right.

Thanks re: the flares!

---[[User:MikeTheRed|MikeTheRed]] 21:08, 3 June 2006 (PDT)

----

The influence of distance still needs to be tested, although it doesn't seem to be an enormous factor. Rather than a complicated graph, I think a few charts with distance = 1, 10 and 20 would probably tell the story more clearly. The distance formula might even prove to be something really simple, like +1 distance = -1% chance.

The hardest aliens to MC are Sectopods and Cyberdiscs: look at the [[Psionics#Summary_of_Alien_Psionic_Resistance]] section I added. At distance 1 on Superhuman you'll need 93 to 192 Attack Strength to achieve 1% to 100% chance. Assuming Psi Str 90, that's Skill 52 to 107.

Now vs. the strongest attacker: Superhuman Ethereal Commander, attack str 88. You'll need a Resistance of 132 to be totally immune to panics from one adjacent to you -- that's str 100, skill 160, or str 90, skill 210. Against MC, it's str 100/skill 60 or str 90/skill 110. In practice you won't be right next to them, so you can probably go a bit lower. They'll focus on the weakest soldiers anyhow, which in practice means a couple of decoys in with some supertroopers is a good strategy.

82.6%, yes.

--[[User:Ethereal Cereal|Ethereal Cereal]] 21:51, 3 June 2006 (PDT)

OpenOffice.org is CPU-bound when converting the graph from 2D to 3D. [XCOM Psi Str/Sk 90/0-107, alien Psi Str/Sk 25-116/0; I'm on a 1GHz Pentium III/512MB] Not sure how ColdFusion single-IP demo would do yet (would have to reinstall), but the UI options look better in OpenOffice.org.

I'll attempt the transition later today (when I know I'll be away from the system and positively not working). I just need to be able to take a screenshot.

You probably already noticed this: even if a bug permitted a 0 Psi Skill operative to use a Psi Amp, the success chance of MC is still negative.

Also (thinking about the testing anomaly MikeTheRed had): The floating-point change in success rate from an increase of 1 in Psi Skill is 1.9 at 95 Psi Str. Integer truncation would make this 1...leaving the floating-point formula overestimating by 39.6%. At the precision of reporting, this works.

[Edit: but does *not* work against the initial regression. So, no good.]

---[[User:Zaimoni|Zaimoni]] 9:51, 4 June 2006 (CDT)

Got a chance to run the bar graph this morning...no go, OpenOffice.org doesn't like a horde of data points on both axes.

But...this particular graph is essentially a plane. It should be hand-drawable, even if the more complicated ones aren't.

---[[User:Zaimoni|Zaimoni]] 8:35, 5 June 2006 (CDT)

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Hi Zaimoni... I'm not sure I understand the differences you talk about. You mean you can get your s/w to make a graph where you've specified the points by hand? Anyway, if you take a shot at most anything, we'd be able to give feedback... a picture's worth a thousand words. Thanks for working on it! ---[[User:MikeTheRed|MikeTheRed]] 06:36, 5 June 2006 (PDT)

Somewhat. Layer 1 of the spreadsheet is the raw data to be graphed (took about five minutes to set up). If I was going to commit to this representation, I'd go back and make the XCOM Psi Str and Alien Psi Skill configurable. So it's trying to graph data points (the MC success chances) on 0-107 by 25-116. I was planning to rotate the view after getting the initial graph up on Layer 2. [Time loading is not favorable for working further on this today.]

OpenOffice.org's autoscaling isn't compensating properly. I haven't checked how to suppress the "color key" that was auto-generated for Alien Psi Str — it's not leaving enough space for the vertical bars to even be 1 pixel in size. The result is decidedly flat, with "correct" vertical range.

As a bar graph, I could get away with subsampling (but don't have a clean way to do it). Yes, it should be possible to correctly graph this (as a plane in three-dimensional space) with only four data points: the corners.

---[[User:Zaimoni|Zaimoni]] 12:39, 7 June 2006 (CDT)

== Psychic Farm ==
There's a sort of tactic I use which may fit into this article. It's blatant simple: building a base with a couple Living Quarters and as many
Psionic Laboratories as possible, hire the entire population of a small town and get them into psionic training. There may be a pre-selection for soldiers with appalling stats. I don't know what happens to veterans, but in my games by the time I get Psionic Labs money is not a constraint anymore, so I find this industrial breeding quite viable. What do the savvy say about this?--[[User:Trotsky|Trotsky]] 02:40, 11 July 2006 (PDT)
----
Hiya Trotsky,

That's what I do. You might want to see my info on [[Raw_recruit_statistical_likelihood|recruit statistics]] and [[Hiring/firing]] (esp. the last bullet under General Info). If you get the full 1,000 recruits per month, about 50 will have psi strength of 95+. Taking other stats into consideration, one or two dozen will be top-notch recruits.

I only have 2 or 3 actual combat squads. One of my less-busy bases serves as initial receiving for batches of ~100 (no psi labs needed), and other un-busy bases get the recruits who made the initial cut farmed out to them, for psi evaluation (lots of psi labs needed).

FWIW I have an applet that reads a savegame; I run it when a new batch of recruits shows up, and it prints out who to keep based on a prioritization. It's ordered by base and soldier names at that base so I go directly to Sell/Sack and dump the ones that didn't cut it, without needing to look at their stats in the game. Then those guys move on to your "psychic farm" bases for psi evaluation. Before I wrote the applet, I would stick a little plus sign next to the names of the guys to keep as I reviewed them in the Soldier Stats screen, so I'd know who to Sack.

Because you can only have 250 soldiers max, and some are devoted to combat or other duties, depending on how you draw the line on initial recruit stats (and how hard you want to work at it), plus the fact that psi results only come up at the end of the month and you need to have the next batch on hand for next month's evaluation... this all means that there's actually only ~100 noobs undergoing psi evaluation on any given month. Also, the number of new recruits you order in batches goes down from the beginning of the month to its end, since you only have a window of ~100 to work with initially. At least, that's how it works for me.

If I run a game a long time, over time what happens is that the bar for psi strength in my 2-3 active combat crews rises over time. Each month, the few high-psi recruits push a few vets below the bar. The best of these vets are farmed out to lesser bases, in case of attack. Of course, any of us could've won long before this point; we're playing just for the joy of play.

Despite all the above, if a soldier has good psi strength, almost anybody can become a superman, given enough [[Experience#Soldier_Advancement|combat]]. The difference between the worst recruit and the best is only about a dozen combats (assuming they can get 3 actions for firing and reaction each combat).

---[[User:MikeTheRed|MikeTheRed]] 16:14, 11 July 2006 (PDT)
:I see people creating scripts and stuff to analyse the game files to know who to sack, psi training hundreds of soldiers to finally only keep 2 or 3 guys... All of this is time consuming at best. Why don't you just hex-edit the games file to improve the soldiers? Or hack the game to always show the psi strength, or generate only ubersoldiers? Yeah this would be cheating. But screening 1000 soldiers a month... [[User:Seb76|Seb76]] 03:20, 25 May 2008 (PDT)

== Suggestions for Psi Defence ==

The first aim on missions is to pick off as many aliens as possible without them sighting you. With luck you can break their morale before you get a single psi-attack. Once a soldier is seen the aliens will often, but not always, pick off your weakest soldiers mercilesly (I've had a soldier with 83 strenth panicked as the sole attack during a mission, strangely). The second aim is to get your vulnerable soldiers disarmed so they can soak up all the psi-attacks harmlessly. You can do this by getting soldiers to drop everything when they return to your control, making sure weapons are stored on the ground instead of in hand, or stunning and reviving soldiers. Killing a soldier under alien control will only result result in another soldier being targetted. As you can't keep all your soldiers harmless all the time you should use all available cover to make sure that your troops cannot see each other. This reduces the damage if a soldier gets controlled. Don't use explosive weapons. Don't hold primed grenades between turns. Don't use proximity grenades close to your troops and clear any when soldiers panic in their direction.

Once a mission is completed you can rename the soldiers to record their Psi capability. I'd stick an X on their name, say, for poor defence. Soldiers which look like they have good Psi strength can be marked for training. Soldiers with poor defence will be no use in Cydonia so they can be sacked, used as scouts, or used as decoys on later Psi missions.

On Psi-attack, I think it's worth mentioning that if you stun an alien while it is under mind control then it will not be captured at the end of the mission. I have lost a commander this way.

- Egor

Xconman...

Is this how you add your 2cents? I've been playing xcom since PS1. I loved it but hated the load time on it. The PC version was faster but somehow not as good. Anyway, I've found the most successful preventive tactic vs psionics is to not bunch your troops together. If an alien sees you and you don't kill it that turn, it's a sure bet someone will be controlled. (someone may be controlled anyway but it cuts the result by at least half) I've played the game so much the tactical aspect is predicable (so easy) for me except when you have powerful psionics against you so I started to send out 2-3 man squads (spaced apart) toward the target and the rest of my squad spread to the 4 corners of the map. As troops die you send in one or two more troops. I've found that I hardly recieve psionic attacks when I approach the enemy this way.

Xconman...

This is a cheat. On Psionic farming. Create a univeristy base devoted to psionics, say 100 students. Forward the game by not attacking and ignoring everything. See the results of the troops and copy down their names. Restart a day later and expell all "failures" and hire the amount of students equal to vacant spaces. Repeat as often as you have (time) no life for. lol
I've found the cpu registers the psionic power/skill when the charcter is created and not when the month is up. I've had 37 characters with 100 ps str this way in 3 game months. (it took 5 hours off my life though...)

: You might want to use colons : to indent your paragraphs. Putting a space in front of it is the shortcut for preformatted text - and that has a tendency to look unpleasant depending on your screen settings. Also you can sign your posts by entering four tildes <nowiki>~~~~</nowiki> rather than head it with your username.

: When a new recruit is hired, psi skill is set to 0, while psi strength is a random roll from 0 to 100. So yes, the strength level is predetermined the moment the soldier is hired. The game only reveals the psi strenth stat when the psi skill stat is greater than 0, which is where the first month in the labs comes in.

: With a bit of code diving, we've confirmed the 20 turn grace period and the 2-remaining alien condition before psionics are launched. But have we done so with the visual aspect of it? -[[User:NKF|NKF]] 02:01, 25 May 2008 (PDT)

::NKF: No, seems I somewhat jumped the gun on that one. For what it's worth, I've noticed that the AI gets smarter after about turn 20(what with the noted leaving of the UFO and stalking of your units) as well as a smart AI when only a handful of aliens survived the crash. (This may well be why I've had the lone alien from the small scout ambush my troops on more than one occassion; he knows where they are at all times.) Just my theories. [[User:Arrow Quivershaft|Arrow Quivershaft]] 03:24, 25 May 2008 (PDT)
::The code dig was not related to psi attacks in particular. The game sets the visibility flag to 1 for all XCOM units in the 2 cases you mentionned, no more no less. [[User:Seb76|Seb76]] 03:42, 25 May 2008 (PDT)
::Edit: I did a quick check: the game does not seem to test the visibility flag when searching for a target! If you patch offset 0x469B in the CE edition from 0x02 to 0x03, it _might_ test for it. Feel free to test... [[User:Seb76|Seb76]] 03:57, 25 May 2008 (PDT)

----[[User:wfames|wfames]] 2:38, 19 Jan 2009 (EST)
First of all, I'm a new player, and I've found this website indescribably helpful. Thanks a lot! I have a question about psionics. I'm playing the Steam version, and psionics is not turning out to be the game-breakingly-powerful weapon I've heard it described as. I can never seem to MC more than 1 alien 1 time during a mission. Even a Psi Strength 99 soldier can't grab Sectoid Solders with any reliability. I chalked it up to lack of skill, but find that 1 of the first half-dozen attempts for a single battle works great, and then it never works again. And I have NEVER seen any of my soldiers gain increased Psi Skill, though apparently it's supposed to go up like crazy. I've observed the same phenomenon in TFTD. Am I doing something wrong? I assumed MC was incredibly unreliable, but I don't even bother to use what's supposedly the most powerful ability in the game. And man, I could use it in TFTD right now, that game is rough...

Thanks a lot, I really appreciate the time you guys put into this.

Talk:Psionics

2009-01-19T07:37:33Z

Wfames: question:psionics not working?

Just had a thought on the formula!

What if the "Psionic Combat Strength" formula was a''' ' + ' '''rather than a''' ' * ' '''?

It would mean the example Soldier would have a PCS of 111, rather than 1520, and the defending Muton would have:

Panic Chance = 76%
MC Chance = 56%

These numbers seem more reasonable, don't you think?

--[[User:Danial|Danial]] 15:32, 19 Nov 2005 (PST)
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Right, it sounds '''much''' more reasonable now. My actual results were 1192 successes out of 2420 tries = 49.26% success rate. The MCer was right next to MC victim, and we know distance introduces ''some'' kind of decrease to base chance. That's the good news. The bad news is that I also tested psi str 95, skill 44 (and some higher skill levels) and never failed to MC ''once'' with these better MCers. Using your revision, a psi str 95, skill 44 guy should have had a success rate of 84% vs. a beginner Muton soldier (psi str 25, skill 0), not 100%. My higher-skill guys were also right next to their MC victims. So, to me the first example makes sense relative to your idea (fits base chance, plus a little distance adds a little more), but the second example counters it.

Still, it sounds WAY better than 1500% :)

I sure wish psi testing wasn't so labor intensive. I got those 2400 counts doing all that experience testing... not interested in doing it again, just for psi equations. At least not at the moment. :P ---[[User:MikeTheRed|MikeTheRed]] 21:12, 23 Nov 2005 (PST)
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Question: why is the Sectopod's psionic resistance listed as N/A? I've mind-controlled sectopods (or at least one square of a sectopod) on many occasions. I usually have it shoot itself, since it can target one of its other, non-MC'ed squares. From my anecdotal experience, their psi resistance seems somewhat high. --[[User:Papa Legba|Papa Legba]] 14:19, 2 February 2006 (PST)
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Answer: If you look on the alien summaries in the wiki they all have a PSI resistance listed, except the Sectopod. Since it's not listed anyplace I put N/A. Feel free to put it where it belongs in the list if you have enough experience to feel comfortable ranking it. --[[User:Darksun|Darksun]]
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Darksun, I took the liberty of signing your name for you, and making a separator line. Why not say a word about yourself under [[User:Darksun]] and also, use four dashes (----) to demarcate entries. For more on the basics of wiki'ing, see NKF's "Community Portal" at the bottom of the homepage. Past all that - welcome, fellow XCOMMIE! We were all wiki noobs once. But not everybody loves XCOM. You must. Welcome aboard!

Proceeding right along to flagellating, laugh - Where are you folks talking about Sectopod psi resistance being "N/A"? I see their Psi Strength as 100, and their Psi Skill as 0 at Beginner; Psi Strenth 116 and Skill still 0 at Superhuman. In this respect, they match Cyberdisks. What do you folks mean by Psi "resistance"? Do you know the math behind the psi equations? I haven't been able to figure it out. But the stats I just listed are ones hacked out of the game... Zombie is going to present a full precis' some time soon.

Great speaking at ya ... keep on contributing, Darksun!! --[[User:MikeTheRed|MikeTheRed]]

== Alien psionic resistance ==

I haven't tried mind-controlling Cyberdiscs much, but if, as I've read elsewhere, both Sectopods and Cyberdiscs have have a Psi Strength of 100, they should probably both be classed "extremely high".
--[[User:Ethereal Cereal|Ethereal Cereal]] 10:30, 4 May 2006 (PDT)

== Psionic testing ==

I started doing some testing to figure out the psionics formula.

Initial finding: ''distance'' takes the hypotenuse into account. I'm not sure if the actual Pythagorean formula is used, but I can say this much: an Ethereal was able to panic a moderately-psi-weak soldier at 30 squares along the horizontal but not at 30 squares along the diagonal.

Second finding: the difference in "difficulty" between MC and panic is definitely 20 points (although that may not be percent). A soldier with 97 Psi strength, 0 Psi skill standing adjacent to an Ethereal Leader (60 str/45 skill) could not be panicked at all, but 96 Psi str could (often). The same soldier with 77 Psi str couldn't be mind-controlled, but could at 76 Psi str. ''With further testing, I see that 60/45 vs. 97 should succeed occasionally; I might retest this for greater precision, although the +20 still seems to hold.''

Third finding: A soldier with 99 Psi str/0 skill could ''just barely'' be panicked by an adjacent Ethereal with 63/45. I couldn't count how often the Ethereal succeeded, but it was something like 1%-2% of the time. The same soldier was panicked just as infrequently by an Ethereal with 45/63 (str & skill reversed), and much more often by an Ethereal with 54/54. This pretty strongly suggests the attack portion of the formula involves psi str & skill multiplied together.

Data points collected so far:
*Ethereal, 63/45, just barely panicked soldier, 99/0
*Ethereal 40/40 just barely panicked soldier 75/0
*Ethereal 27/27 (multiplied together = 729) just barely panicked soldier 57/0
*Ethereal 10/73 (multiplied = 730) just barely panicked soldier 57/0
**''this confirms that attacking is based on str*skill
*Ethereal 18/18 just barely panicked soldier 49/0
*Ethereal 1/1 just barely panicked soldier 43/0
*Ethereal 1/1 just barely panicked soldier 1/210
**''this confirms Psi skill / 5 is used in calculating defense; 1 + (210/5) = 43''

I also tested Ethereal 0/1 (no psi str, 1 pt. skill); it still attacked, but did not attack at 0 pts. skill no matter how high psi str was (no surprise there, otherwise all units would do psi attacks).

I ran the points through a curve-fitting program and got a nice and simple answer:

attack strength = psi str * psi skill '''/ 50'''
defense strength = psi str + (psi skill / 5)

Panic Attack chance = 44% + attack strength - defense strength
Mind Control Attack chance = 24% + attack strength - defense strength

The formula has held up under limited further testing; I'm satisfied it's correct. I invite others to test it more than I have.

The impact of distance has yet to be tested, but it should be easy to figure out now.

--[[User:Ethereal Cereal|Ethereal Cereal]] 22:03, 26 May 2006 (PDT)

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There is a reasonable approximation to the Pythagorean formula (in the plane) that could have been used, that doesn't require loops or floating-point math:

max( | Δx | , | Δy | ) + ½min( | Δx | , | Δy | )

where Δ_ := _2 - _1.

It overestimates slightly. I haven't thought through how this would generalize to 3D. [Yanked from Moria, Angband, and variants...think it's too basic to copyright, though.]

One way to test whether the distance estimator is no greater than true Pythagorean formula by working out the greatest distance (pure x or pure y) that MC/Panic is not 0%, then testing on a diagonal with a "computed same". An integer-math overestimator (like the above) would by 0%.

Muliple of 5 allows replacing the diagonal with a suitably scaled 3-4-5 triangle...should work as well for testing.

--[[User:Zaimoni|Zaimoni]] 2:38PM, 26 May 2006 (CDT)

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Wow... good approach to teasing this out, Ethereal!

Am I doing this right? I plugged in numbers for Muton, 25/0, Me 95/44, and got 83% MC Base Chance... But in much repeated testing (when learning about experience counters) it seemed quite solid that I was MC'ing him about half the time. Say 45-55% of the time. This was when right next to each other. Is 83% right for your equations?

Zaimoni, re: your equation, see [[Explosions#Distance_from_Ground_Zero]]. XCOM seems to use a fairly simple approach that doesn't involve Pythagoras per se. Since it's based on a very old engine, much of its stuff is integer based. Cool deal on the deltas and other wiki symbols - I wish I knew about them sooner! Actually I know where wiki symbol tables are... just didn't bother to look up so many symbols. :P

Nobody has tackled 3D distance yet, but I may soon, in studying illumination.

Once the equations are well known (maybe they are already), I imagine some cool 3D topographical graphs of the various factors (skill and strength, you vs. enemy) could be made. Do either of you have surface graph s/w at hand? All I've got at the moment is Excel. :(

Great work! Also thanks for cleaning up the page in general, Eth.

---[[User:MikeTheRed|MikeTheRed]] 22:24, 2 June 2006 (PDT)

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I suspect you've misremembered the details of your tests. The 49.26% success rate out of 2400 trials that you quote above would have been for your 95/16 soldier doing panics, not MCs: 44 + [95*16/50 = 30.4] - 25 = 49.4%, almost exactly the same as your 49.26%. A 95/44 doing panics would always succeed: 102.6%. A 95/44 doing MCs would succeed 82.6% of the time.

--[[User:Ethereal Cereal|Ethereal Cereal]] 11:06, 3 June 2006 (PDT)

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Ah, there's that data. Thanks for reminding me. I can't remember what I put in which discussions and was going to dig it out of my db.

No, it was MCs. Indeed I relied on the lack of seeing an enemy, if I got moving too fast and couldn't remember if I successfully MC'd. Attention starts to wander with such highly repetitive testing. This was before I realized the following...

Anyone doing repetitive psi testing can readily and accurately get the number of positive results from the [[UNITREF.DAT]] Psi byte [84] if you work it right. Note the turn you start psi attempts. Then do exactly 2 or 3 psi Attempts each turn, as your TUs allow. Then note the turn you stop and get the delta. Turns x Attempts/Turn = Attempts. A failed psi attempt adds 1 to [84] and a successful attempt adds 3, so the number of successes is: ([84]-Attempts)/2. Be careful during testing marathons because the byte wraps around at 255 (=85 straight successes, or 28.3 turns at 3 successful attempts per turn). Then it starts counting again so actually even this can be dealt with by adding 255 if you're on top of it. If anybody wants an applet that shows Unitref experience values on the fly, let me know. It's great for building experience. Right now it's embedded within my mdb though... I'd have to tease it out.

I'm using XCOM DOS which I once ran XcomUtil on, if that matters.

Hmm.

---[[User:MikeTheRed|MikeTheRed]] 12:21, 3 June 2006 (PDT)

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Distance...ok, no reason for the game to use multiple 2-d distance formulæ.

I have software set up to render 3D graphs. Is there anything on the site that jumps out as "would like to see first"? I'd rather wait until the psi formulæ are calibrated first before graphing those.

Ethereal: What I see posted is test data for ethereal MC human. Do you have test data for human MC ethereal as well? [That would test whether the game calculations are symmetrical.]

---[[User:Zaimoni|Zaimoni]] 2:37, 3 June 2006 (EDT)

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It ''is'' possible X-COM units get a different formula from aliens -- I only tested an alien doing psi, as it was more automated -- the thing would psi without my having to control it.

I'm not not volunteering to test x-com units for the time being -- it's a bit more laborious -- but if I ''had'' to test it, I'd do a small number of trials of 35/16, 50/51, and 100/51 soldiers trying to MC (not panic) an adjacent Muton, which should succeed 10.2%, 50% and 101% of the time.

Feel free to test it before I do. ;-P

Oh, and nice work on the flares, Mike.

--[[User:Ethereal Cereal|Ethereal Cereal]] 12:50, 3 June 2006 (PDT)

----

Sounds cool, Zaimoni... As for "like to see",

Once my troops have psi ability, I try to get 90+ psi strength guys. Then the question becomes "at psi str 90, at what psi skill point are most/all aliens certain to be MC'ed?" In my experience, it's somewhere around skill 40-60... Anything that might show this, or show how you fare relative to aliens at, say, STR 90, is something I've always wanted. However it might be done. In one sense you could simply plug the "worst" psi alien (Ethereal CDR?) into Eth's equations to get the final answer. But it'd be good to see the lay of the land.

If you make the simplifying assumption that many of your targets are psi skill 0, there's one less variable. Additional graphs can be done later just for the psi-capable aliens... first things first though...

Taking the above into consideration, then, XCOM Psi Skill (Str=90) vs. Alien Psi Strength (Skill=0) vs. Success rate is one 3D graph that could be made. If you can do a 4th dimension as color, you could replace the Success rate axis with XCOM Psi Str, then have color indicate success rate, from primary red for "no way" through yellow for "sometimes" to primary green for "always". Or something like that. It'd also be nice but not critical to have annotations for where various aliens lie along their dimension. I can supply this info if you want. Which reminds me: Eth, Zombie and others found some errors in Aztec's table (which came from the OSG). Just a few percent of them, but they're definitely there (I can't remember where). I've hacked alien stats straight out of GEOSCAPE... see the alien stats page. I believe Zombie has found these to be correct, but he has not yet given the final word.

Zai, as far as I'm concerned, you can model using EC's equation already, if you have the time... I'm sure his equations are very close, if not spot on, and even if not, it may show key places to test and otherwise support further testing. E.g., both aliens and XCOM can readily have their relevant values hacked to test for boundary conditions of 0% and 100% success. Plus once it's set up it shouldn't be hard to tweak the equation and voila, the graphs update. But if you don't have the time - eh, it's all volunteer work anyway.

Eth, I suppose it's possible aliens vs. humans is different. They are known to have some differences in functionality, such as night vision. I don't know if I'll be able to test, but it definitely intrigues me. BTW I said somewhere else that I was looking into automating the XCOM interface in order to do psi testing. I have concluded that I can't do it. At least not the way I was hoping to. Oh well. Still, my belated realization that one can use Unitref[84] to count psi successes is a real boon to repetitive testing. So we'll see. Thanks for suggestions on what to test if I do. By the way, did I do that 83% correct? I just want to make sure I'm doing the math right.

Thanks re: the flares!

---[[User:MikeTheRed|MikeTheRed]] 21:08, 3 June 2006 (PDT)

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The influence of distance still needs to be tested, although it doesn't seem to be an enormous factor. Rather than a complicated graph, I think a few charts with distance = 1, 10 and 20 would probably tell the story more clearly. The distance formula might even prove to be something really simple, like +1 distance = -1% chance.

The hardest aliens to MC are Sectopods and Cyberdiscs: look at the [[Psionics#Summary_of_Alien_Psionic_Resistance]] section I added. At distance 1 on Superhuman you'll need 93 to 192 Attack Strength to achieve 1% to 100% chance. Assuming Psi Str 90, that's Skill 52 to 107.

Now vs. the strongest attacker: Superhuman Ethereal Commander, attack str 88. You'll need a Resistance of 132 to be totally immune to panics from one adjacent to you -- that's str 100, skill 160, or str 90, skill 210. Against MC, it's str 100/skill 60 or str 90/skill 110. In practice you won't be right next to them, so you can probably go a bit lower. They'll focus on the weakest soldiers anyhow, which in practice means a couple of decoys in with some supertroopers is a good strategy.

82.6%, yes.

--[[User:Ethereal Cereal|Ethereal Cereal]] 21:51, 3 June 2006 (PDT)

OpenOffice.org is CPU-bound when converting the graph from 2D to 3D. [XCOM Psi Str/Sk 90/0-107, alien Psi Str/Sk 25-116/0; I'm on a 1GHz Pentium III/512MB] Not sure how ColdFusion single-IP demo would do yet (would have to reinstall), but the UI options look better in OpenOffice.org.

I'll attempt the transition later today (when I know I'll be away from the system and positively not working). I just need to be able to take a screenshot.

You probably already noticed this: even if a bug permitted a 0 Psi Skill operative to use a Psi Amp, the success chance of MC is still negative.

Also (thinking about the testing anomaly MikeTheRed had): The floating-point change in success rate from an increase of 1 in Psi Skill is 1.9 at 95 Psi Str. Integer truncation would make this 1...leaving the floating-point formula overestimating by 39.6%. At the precision of reporting, this works.

[Edit: but does *not* work against the initial regression. So, no good.]

---[[User:Zaimoni|Zaimoni]] 9:51, 4 June 2006 (CDT)

Got a chance to run the bar graph this morning...no go, OpenOffice.org doesn't like a horde of data points on both axes.

But...this particular graph is essentially a plane. It should be hand-drawable, even if the more complicated ones aren't.

---[[User:Zaimoni|Zaimoni]] 8:35, 5 June 2006 (CDT)

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Hi Zaimoni... I'm not sure I understand the differences you talk about. You mean you can get your s/w to make a graph where you've specified the points by hand? Anyway, if you take a shot at most anything, we'd be able to give feedback... a picture's worth a thousand words. Thanks for working on it! ---[[User:MikeTheRed|MikeTheRed]] 06:36, 5 June 2006 (PDT)

Somewhat. Layer 1 of the spreadsheet is the raw data to be graphed (took about five minutes to set up). If I was going to commit to this representation, I'd go back and make the XCOM Psi Str and Alien Psi Skill configurable. So it's trying to graph data points (the MC success chances) on 0-107 by 25-116. I was planning to rotate the view after getting the initial graph up on Layer 2. [Time loading is not favorable for working further on this today.]

OpenOffice.org's autoscaling isn't compensating properly. I haven't checked how to suppress the "color key" that was auto-generated for Alien Psi Str — it's not leaving enough space for the vertical bars to even be 1 pixel in size. The result is decidedly flat, with "correct" vertical range.

As a bar graph, I could get away with subsampling (but don't have a clean way to do it). Yes, it should be possible to correctly graph this (as a plane in three-dimensional space) with only four data points: the corners.

---[[User:Zaimoni|Zaimoni]] 12:39, 7 June 2006 (CDT)

== Psychic Farm ==
There's a sort of tactic I use which may fit into this article. It's blatant simple: building a base with a couple Living Quarters and as many
Psionic Laboratories as possible, hire the entire population of a small town and get them into psionic training. There may be a pre-selection for soldiers with appalling stats. I don't know what happens to veterans, but in my games by the time I get Psionic Labs money is not a constraint anymore, so I find this industrial breeding quite viable. What do the savvy say about this?--[[User:Trotsky|Trotsky]] 02:40, 11 July 2006 (PDT)
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Hiya Trotsky,

That's what I do. You might want to see my info on [[Raw_recruit_statistical_likelihood|recruit statistics]] and [[Hiring/firing]] (esp. the last bullet under General Info). If you get the full 1,000 recruits per month, about 50 will have psi strength of 95+. Taking other stats into consideration, one or two dozen will be top-notch recruits.

I only have 2 or 3 actual combat squads. One of my less-busy bases serves as initial receiving for batches of ~100 (no psi labs needed), and other un-busy bases get the recruits who made the initial cut farmed out to them, for psi evaluation (lots of psi labs needed).

FWIW I have an applet that reads a savegame; I run it when a new batch of recruits shows up, and it prints out who to keep based on a prioritization. It's ordered by base and soldier names at that base so I go directly to Sell/Sack and dump the ones that didn't cut it, without needing to look at their stats in the game. Then those guys move on to your "psychic farm" bases for psi evaluation. Before I wrote the applet, I would stick a little plus sign next to the names of the guys to keep as I reviewed them in the Soldier Stats screen, so I'd know who to Sack.

Because you can only have 250 soldiers max, and some are devoted to combat or other duties, depending on how you draw the line on initial recruit stats (and how hard you want to work at it), plus the fact that psi results only come up at the end of the month and you need to have the next batch on hand for next month's evaluation... this all means that there's actually only ~100 noobs undergoing psi evaluation on any given month. Also, the number of new recruits you order in batches goes down from the beginning of the month to its end, since you only have a window of ~100 to work with initially. At least, that's how it works for me.

If I run a game a long time, over time what happens is that the bar for psi strength in my 2-3 active combat crews rises over time. Each month, the few high-psi recruits push a few vets below the bar. The best of these vets are farmed out to lesser bases, in case of attack. Of course, any of us could've won long before this point; we're playing just for the joy of play.

Despite all the above, if a soldier has good psi strength, almost anybody can become a superman, given enough [[Experience#Soldier_Advancement|combat]]. The difference between the worst recruit and the best is only about a dozen combats (assuming they can get 3 actions for firing and reaction each combat).

---[[User:MikeTheRed|MikeTheRed]] 16:14, 11 July 2006 (PDT)
:I see people creating scripts and stuff to analyse the game files to know who to sack, psi training hundreds of soldiers to finally only keep 2 or 3 guys... All of this is time consuming at best. Why don't you just hex-edit the games file to improve the soldiers? Or hack the game to always show the psi strength, or generate only ubersoldiers? Yeah this would be cheating. But screening 1000 soldiers a month... [[User:Seb76|Seb76]] 03:20, 25 May 2008 (PDT)

== Suggestions for Psi Defence ==

The first aim on missions is to pick off as many aliens as possible without them sighting you. With luck you can break their morale before you get a single psi-attack. Once a soldier is seen the aliens will often, but not always, pick off your weakest soldiers mercilesly (I've had a soldier with 83 strenth panicked as the sole attack during a mission, strangely). The second aim is to get your vulnerable soldiers disarmed so they can soak up all the psi-attacks harmlessly. You can do this by getting soldiers to drop everything when they return to your control, making sure weapons are stored on the ground instead of in hand, or stunning and reviving soldiers. Killing a soldier under alien control will only result result in another soldier being targetted. As you can't keep all your soldiers harmless all the time you should use all available cover to make sure that your troops cannot see each other. This reduces the damage if a soldier gets controlled. Don't use explosive weapons. Don't hold primed grenades between turns. Don't use proximity grenades close to your troops and clear any when soldiers panic in their direction.

Once a mission is completed you can rename the soldiers to record their Psi capability. I'd stick an X on their name, say, for poor defence. Soldiers which look like they have good Psi strength can be marked for training. Soldiers with poor defence will be no use in Cydonia so they can be sacked, used as scouts, or used as decoys on later Psi missions.

On Psi-attack, I think it's worth mentioning that if you stun an alien while it is under mind control then it will not be captured at the end of the mission. I have lost a commander this way.

- Egor

Xconman...

Is this how you add your 2cents? I've been playing xcom since PS1. I loved it but hated the load time on it. The PC version was faster but somehow not as good. Anyway, I've found the most successful preventive tactic vs psionics is to not bunch your troops together. If an alien sees you and you don't kill it that turn, it's a sure bet someone will be controlled. (someone may be controlled anyway but it cuts the result by at least half) I've played the game so much the tactical aspect is predicable (so easy) for me except when you have powerful psionics against you so I started to send out 2-3 man squads (spaced apart) toward the target and the rest of my squad spread to the 4 corners of the map. As troops die you send in one or two more troops. I've found that I hardly recieve psionic attacks when I approach the enemy this way.

Xconman...

This is a cheat. On Psionic farming. Create a univeristy base devoted to psionics, say 100 students. Forward the game by not attacking and ignoring everything. See the results of the troops and copy down their names. Restart a day later and expell all "failures" and hire the amount of students equal to vacant spaces. Repeat as often as you have (time) no life for. lol
I've found the cpu registers the psionic power/skill when the charcter is created and not when the month is up. I've had 37 characters with 100 ps str this way in 3 game months. (it took 5 hours off my life though...)

: You might want to use colons : to indent your paragraphs. Putting a space in front of it is the shortcut for preformatted text - and that has a tendency to look unpleasant depending on your screen settings. Also you can sign your posts by entering four tildes <nowiki>~~~~</nowiki> rather than head it with your username.

: When a new recruit is hired, psi skill is set to 0, while psi strength is a random roll from 0 to 100. So yes, the strength level is predetermined the moment the soldier is hired. The game only reveals the psi strenth stat when the psi skill stat is greater than 0, which is where the first month in the labs comes in.

: With a bit of code diving, we've confirmed the 20 turn grace period and the 2-remaining alien condition before psionics are launched. But have we done so with the visual aspect of it? -[[User:NKF|NKF]] 02:01, 25 May 2008 (PDT)

::NKF: No, seems I somewhat jumped the gun on that one. For what it's worth, I've noticed that the AI gets smarter after about turn 20(what with the noted leaving of the UFO and stalking of your units) as well as a smart AI when only a handful of aliens survived the crash. (This may well be why I've had the lone alien from the small scout ambush my troops on more than one occassion; he knows where they are at all times.) Just my theories. [[User:Arrow Quivershaft|Arrow Quivershaft]] 03:24, 25 May 2008 (PDT)
::The code dig was not related to psi attacks in particular. The game sets the visibility flag to 1 for all XCOM units in the 2 cases you mentionned, no more no less. [[User:Seb76|Seb76]] 03:42, 25 May 2008 (PDT)
::Edit: I did a quick check: the game does not seem to test the visibility flag when searching for a target! If you patch offset 0x469B in the CE edition from 0x02 to 0x03, it _might_ test for it. Feel free to test... [[User:Seb76|Seb76]] 03:57, 25 May 2008 (PDT)

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First of all, I'm a new player, and I've found this website indescribably helpful. Thanks a lot! I have a question about psionics. I'm playing the Steam version, and psionics is not turning out to be the game-breakingly-powerful weapon I've heard it described as. I can never seem to MC more than 1 alien 1 time during a mission. Even a Psi Strength 99 soldier can't grab Sectoid Solders with any reliability. I chalked it up to lack of skill, but find that 1 of the first half-dozen attempts for a single battle works great, and then it never works again. And I have NEVER seen any of my soldiers gain increased Psi Skill, though apparently it's supposed to go up like crazy. I've observed the same phenomenon in TFTD. Am I doing something wrong? I assumed MC was incredibly unreliable, but I don't even bother to use what's supposedly the most powerful ability in the game. And man, I could use it in TFTD right now, that game is rough...

Thanks a lot, I really appreciate the time you guys put into this.