Tactical Layer (EU2012)
This guide contains overarching notes that, while applicable to all difficulties, remain relevant even on Impossible difficulty. For more niche tactics advice, see Tactics.
Combat
Safe Moves and Free Shots
- Bullet Swarm Heavy. Can Fire and Hunker down or Fire and Move out of LoS.
- Squadsight Sniper. Have a soldier in front gain sight, Sniper shoots, then back to safety.
- Lightning Reflexes Assault. Soak one reaction shot for scouting purposes or to open up the playing field.
- Hunker down in high cover against Sectoids, Floaters and Mutons at range.
- Dense Smoke in high cover against Sectoids, Floaters and Mutons at range to be able to act instead of Hunker down.
- Similarly against Sectopods, just need a little more defence (90 Aim on Classic/Impossible) to use Dense Smoke+high cover to still act.
Should I equip Grenade or ...
Grenade. S.C.O.P.E.s only out-compete after your Sniper gets Lasers, and only because the Sniper class is never in range to use Grenades. Before then, Grenades offer too much utility (and damage) and the cover destroyed simply restores so much hit chance plus Crit when needed. There could be an argument for Nano-Fiber Vests, but it is essentially reliant on suboptimal tactics. There's always the chance of running out of HP with them.
Vision Tricks
When there are no more free shots, safe moves to exhaust or if the enemy is too much to overcome at the moment, it's time to pull off a 0% chance to hit tactic, avoiding line of sight (LoS). The reason for this is that AI tends to walk offensively in fog, giving them a chance to misposition themselves if you create fog on purpose. "The supreme art of war is to subdue the enemy without fighting." This is a double-edged sword considering the nature of being outnumbered every mission, but it is necessary in Enemy Unknown. The aliens have the leisure of being on the offense/assertive, while the player must always play for defense/reaction.
Be warned, using any of these vision tricks can mean being pinned if you're unable to defend from potential encroachment/flanks, since the AI will almost always Overwatch in the fog thereby incurring a necessary cost if outmaneuvered. This is how the game is more chess like as originally promised; it's absolutely necessary to think through all the possible enemy moves. The reverse is less true for them, it matters less that you've pinned the enemy since they can either take the shot, if you allow a non 1%, or they can Overwatch and incur a cost for flanking if the paths are visible.
Connected Cover
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Adjacent cover provides visual cover to the unit's peeking tiles. The only way for an attacker to target a unit behind connected high cover is to circumvent the object responsible.
Off Cover
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Stepping off of cover prevents peeking all together, at the expense of being uncovered if caught. In cases where there isn't any connected cover or avoiding destructible cover, this may be your only available option to cut off LoS.
Hills
Hills are doubled up low cover platforms, commonly found during UFO missions. At ground level, they block vision of other ground level units on the other side, just like high cover would.
Loosely Connected Cover
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Loosely connected cover is any combination of disconnected cover that is visually connected at certain vantage points, blocking a considerable amount of vision. They can also be quite tricky/deceptive positions to fight from, making them tactical pitfalls if analyzed incorrectly.
Hunker Down
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Not usually thought of as a vision trick since the AI can still target Hunkered down units, but when not attacking, the AI essentially moves as if the fog created by Hunker down is real.
IMPORTANT: Knowledge of cover destruction is crucial with extensive usage of Hunker down in LoS, limiting position choice if you don't want to be caught with cover blown.
Out of range
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When cover and LoS blockers are unavailable or tactically nonviable, run out of their blue move+vision range. Vision range is a 17 tile radius.
It is only when all of this is exhausted, i.e. one of your soldiers must end in LoS in regular high/low cover, that it is the time to throw everything against the enemy. If a soldier must end in high cover, all moves ending in high cover is fine. Similar for low cover, etc.
Movement and Squad Formation
Movement
With everything you do, it is important to know which tiles are safe to avoid accidental activation. Your first soldier(s) blue move(s) should be a sweeping motion that clears most, ideally all, of the previously unsafe tiles the rest of the squad will walk on.
Move towards high cover, creep around hills or circumnavigate loosely connected cover to minimize your visual area. If moving towards connected high cover, you may even want to stay off of the corner for a turn until you can get the whole squad caught up and situated, rather than peek immediately. Understanding how to minimize the chance of visual contact is crucial whether you believe staying close together or splitting into separate groups is the right choice for your circumstance. In practice, it's not strictly one or the other. It's important to understand the two styles/concepts so that you know which way to lean after analyzing the map.
Note that on certain (parts of) specific maps, consider also whether you are allowing good cover at the vision perimeter. Sometimes, the intention is to prevent good cover options at the fringes of vision for potential pod activations. Otherwise, it's easy for the game to let it rip.
Close order formation
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Pros
- Minimizing the visual area lessens the chance of pods patrolling in and activating; useful when sneaking towards connected cover
- The entire squad is already centered to fire on any enemies crossing the shared visual perimeter, guaranteeing reaction shots if on Overwatch and/or having the option of a full frontal attack
- Simple to reorient in response to threats
Cons
- May be pinned if high movement aliens scamper forward
- Might not have a way to fallback if cornered
Open order formation
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Pros
- Can reorganize freely within your area of control
- Helpful when creeping around hills, maneuvering across open terrain or scouting complex environments, by mitigating against potential pod ambushes/flanks; listening to sounds can help pinpoint whether this is a real possibility
Cons
- Widening the area of control helps the enemy form a naturally wide encirclement, leaving no vulnerable point of attack
- Regrouping could mean giving up good ground to the enemy
About Roofs
Pros
- Height bonus
- Great for traveling Overwatch
- Unlikely location for initial pod positions
- Can be useful as a highway to outmaneuver the enemy
- Technically one big "vision trick"; ground AI has no legitimate response
Cons
- Activating a pod up there can make things worse
- Impossible to defend if overwhelmed
- Can often be a crutch for not having understood other game fundamentals
Missions
Abduction
Apart from a few exceptions, you can typically expect lots of connected high cover or loosely connected high cover.
UFO
May find connected high cover, but should expect to identify hills and loosely connected 'hills'.
Council
After the first month, they consist entirely of Thin men pods that don't patrol.
Target Extraction and Target Escort
Thin men will drop in, which can be Overwatched, as you escort the target. Take your time.
Bomb Disposal
The pinnacle of the Council mission concept, combining the idea that pods don't patrol with a timer.
- Your first blue move every turn is extremely important. You want to clear fog and activate pods now, but it's a balancing act between being reckless or being slow.
- Dash everyone onto a safe tile to catch up when not engaging with any enemies.
- There are no drop-ins so traveling Overwatch is completely pointless, except at the end when bomb is diffused.
AI behaviors
On player actions
Hunker down
As mentioned, Hunker down is a vision trick, but also formidable as a 1% hit chance bait that the AI will occasionally take. Careful of close range bonus or enemies with aoe abilities.
IMPORTANT: Knowledge of cover destruction is crucial with extensive usage of Hunker down in LoS, limiting position choice if you don't want to be caught with cover blown.
Suppression
Suppressing the AI has a chance to cause them to freeze. Useful when you have the enemy outnumbered to save on resources. Instead of the entire team hiding or increasing defence, a simple suppression from one soldier can allow the rest of the team to take pot shots. Not guaranteed, but unlikely for the AI to run the reaction shot. Careful of close range bonus or enemies with aoe abilities.
On majority pod death
If caught in a tough spot, attempting to kill the majority of each of the pods (1 out of pod of 2 or 2 out of pod of 3) may be a valid strategy if wiping them out completely is not an option. The last one of each pod will have a chance of panicking or going on full retreat. Killing the majority of a pod in one turn has a much greater chance than in separate turns. It is not guaranteed they will do either. Leaving a soldier uncovered/flanked seems to reduce the chances.
- Take note of the units belonging to the same pod. Once the majority of a pod dies, observe the last one.
Panic
- If the last one performs a 'panic' animation (Sectoid shrugs, Floater look left/right, etc.) at the start of their turn, there is a chance it will begin to flee.
- After the panic animation, if the unit makes one blue move into fog, it has successfully fled. If it's a double move or if it remains visible, consider it a 'failed' fleeing attempt (ignore the following).
- Upon a successful flee, the return behavior is GUARANTEED. The return behavior is a blue move out of fog, along with the same panic animation after the blue move.
- After returning, it should forfeit its second action IF it's the last one alive, making it safe to Overwatch trap while anticipating the behavior.
Full retreat
- Last one performs a double move away from the squad. Unlike Panic, there is no animation before or after any moves.
- May blue move into fog one more time if chased next turn.
Brief Notes on Aliens
The primary way of outplaying the AI is knowing their movement range and accounting for their possibilities accordingly.
| Sectoids |
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| Floaters |
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| Thin Men |
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| Outsiders |
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| Chryssalids |
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| Zombies |
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| Mutons |
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| Cyberdiscs |
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| Drones |
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| Berserker |
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| Sectoid Commanders |
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| Muton Elites and Heavy Floaters |
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| Sectopods |
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| Ethereals and Uber Ethereals |
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Enemy Within
In many ways, Enemy Within buffs the player considerably compared to Enemy Unknown. From Seekers/Mechtoids diluting the alien pool, to Medals, to MEC/Gene mods, the bonuses are endless compared to the barebones balance of EU. You can often have a padded soldier that nears 100% hit chance even through high cover. This can help the Heavy, once ridiculed for their low Aim, reveal just how overpowered Bullet Swarm or Rapid Reaction really is.
Combat
In EW, units can no longer utilize peeking tiles if occupied by another unit (other than through occasional bugs). See cover visibility for how that might apply. Remember, this goes both ways meaning aliens can also have their peeking tiles blocked, possibly losing LoS. For close order formation, take care not to block the peeking tile of someone using a high cover corner if you want their reaction shot to trigger.
Another EW quirk is that successful shots might still destroy cover, which could accidentally reveal hidden areas.
Grenade or ...
Once you get Tactical Rigging, you simply don't have to choose. Equip a S.C.O.P.E. along with a Grenade. Or your item of choice, just keep the Grenade.
Meld
Meld canisters basically borrow from the Bomb Disposal concept.
AI
Enemy Within AI has a few changes in comparison to Enemy Unknown. While the shackled AI of Easy/Normal has suboptimal targeting and avoids using certain abilities, EW has included suboptimal action choice for all difficulties. In EU, Overwatch isn't commonly used by the AI while in LoS, only in fog or under Suppression. If they have a shot, they typically fire. Similarly, Poison Spit, Grenade/Bombard and Suppression are used if the AI doesn't like their hit chance. In exchange, EW AI moves forward much more readily, appearing to push their numbers advantage aggressively in fog compared to EU.
- EW has made the AI so that there is a greater chance of choosing Overwatch, Suppression, sometimes even perform a double move, instead Firing. This is suboptimal and effectively means less potential damage. Lest you forget, missed shots have a chance to destroy cover, enabling subsequent aliens to shoot at an uncovered target. On the other hand, Overwatch and Suppression can now further suffocate the player in unfavorable situations and is something more to think about.
- There is the chance that the AI will run the player's Overwatch while already having LoS, whereas they will opt to fire in EU instead. In EU, the AI will usually only run Overwatches near the edge of vision 'accidentally', or to attack a vulnerable target.
- The issue of only one alien, in fog, moving forward to make contact appears to have been fixed. The AI now moves like a swarm in fog and more likely avoids certain stalemate scenarios, pressuring the player to make the offensive choice more.
Aliens
Aliens that do not use cover can now go on Overwatch on activation. This can make flying/robotic enemies slightly more difficult to kill. E.g. a Cyberdisc that Overwatches outside of vision requires Lightning Reflexes if you want to make contact with it immediately. On the other hand, Overwatch puts it in open form, allowing itself to be Crit.
| Mechtoids |
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| Seekers |
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EXALT Covert Operations
One of the only missions that require some foreknowledge of the maps, whether that is reaching and defending the operative in Cover Extraction or reaching and defending the Encoder/Transmitter in Data Recovery. EXALT pods don't patrol very far and can teleport further away depending on your location. After the first turn, EXALT units will start to trickle in from the edge of the map, requiring some traveling Overwatch. They are similar to the Council Target Extraction and Target Escort mission in some sense.
One can only imagine what these missions would be like with better AI and comparable Aim!