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OpenApoc is modelled after the original [[Apocalypse]] and enhances the game experience dramatically.  
'''OpenApoc''' is an open-source C++17 reimplementation of ''[[Apocalypse|X-COM: Apocalypse]]'' (1997). While aiming to faithfully recreate the original game, OpenApoc introduces many improvements, bug fixes, and new features. All new gameplay features are '''optional''' and can be toggled through the '''More Options''' menu.


== General ==
This page documents the known differences between OpenApoc and the original game. For general OpenApoc information, see the [[OpenApoc]] main page.
* None of [[Known Bugs (Apocalypse)|these bugs or limits]].


== Cityscape ==
== Technical Improvements ==
* Aircraft weapons may be unequipped.


== Battlescape ==
OpenApoc runs natively on modern hardware and operating systems, removing the need for DOS emulation:
*
 
* '''Platform support''': Windows (MSVC 2019+), Linux (GCC 8+/Clang 7+), and macOS (including Apple Silicon)
* '''Modern resolutions''': Supports any screen resolution and display scaling, with windowed, fullscreen, and borderless modes
* '''Performance''': Runs at 60 FPS with OpenGL 2.0+ / GLES 3.0 rendering
* '''Human-readable save games''': Game state is stored as XML in ZIP archives, editable with any text editor
* '''Mod support''': Full modding via XML data files, Lua scripting, and a configurable mod loading system
* '''Multi-monitor support''': Can be placed on any display in multi-monitor setups
* '''Configurable audio''': Separate volume controls for music and sound effects
 
== New Gameplay Options ==
 
All new gameplay features are accessible through the '''More Options''' menu and can be individually enabled or disabled. Default values are listed — '''ON''' means the feature is enabled by default in OpenApoc.
 
=== Cityscape Options ===
 
{| class="wikitable sortable"
! Option !! Description !! Default
|-
| Improved city control scheme || Completely new control scheme with modifier keys (see [[#Improved Controls|Improved Controls]] section). Can be disabled to restore vanilla controls. || ON
|-
| Ferry checks relationship when buying || Transtellar checks its relationship with X-COM before providing transport services || ON
|-
| Allow manual use of teleporters in city || Players can manually route vehicles through teleporter buildings for quick transport || ON
|-
| Allow manual ferrying of cargo and non-combatants || Manual control over ferry transport of cargo and non-combat personnel || ON
|-
| Allow soldiers to call taxi || Soldiers can use taxis for transport (restricted to civilians in the original) || ON
|-
| Allow attacking owned vehicles || Allows X-COM to attack its own vehicles (impossible in the original game) || ON
|-
| Call existing transport instead of spawning them || Reuses existing transport vehicles instead of spawning new ones || ON
|-
| Attempt to recover agent equipment dropped in city || Equipment dropped by agents in the city is automatically recovered || ON
|-
| Enforce vehicle cargo limits || Strict enforcement of vehicle cargo capacity || OFF
|-
| Allow nearby vehicles to pick up loot || Nearby X-COM vehicles can collect loot from crash sites || ON
|-
| Allow loot to be stashed in the building || Recovered loot can be deposited in buildings || ON
|-
| Armored roads || Roads have damage reduction, making them harder to destroy || ON
|-
| Unsupported ground vehicles crash || Ground vehicles without road support will crash (weapons and modules may be lost) || ON
|-
| Vehicles crash when entering dimension gates || Vehicles incapable of dimensional travel crash when entering gates || ON
|-
| Vehicles crash when out of fuel || Vehicles crash when their fuel runs out || ON
|-
| Successful raid collapses building || Buildings collapse after a successful raid || OFF
|-
| Any hit on hostile building provokes retaliation || Stray shots hitting hostile buildings trigger retaliation || OFF
|-
| Put market stock on the right side || Market stock displayed on the right side of the transaction screen || ON
|-
| Left clicking icon opens equip menu || Left-clicking a unit's icon opens the equipment screen || OFF
|-
| Skip turbo movement calculations || Performance optimization that skips turbo movement math || OFF
|-
| Allow ATVs to initiate UFO recovery missions || All Terrain Vehicles can start UFO recovery missions || ON
|-
| Show vehicles in current dimension only || Vehicle list filters to show only the current dimension || ON
|-
| Add prefix to non-X-COM vehicles || Non-X-COM vehicles are prefixed with * in vehicle lists for easy identification || ON
|-
| Don't follow vehicles in strategy view || Disables automatic camera following in strategy (isometric) view || OFF
|-
| Use currency formatting || Monetary values displayed with currency formatting (e.g., $1,234,567) || ON
|}
 
'''Other Cityscape differences:'''
* Aircraft weapons may be unequipped (not possible in the original game)
 
=== Battlescape Options ===
 
{| class="wikitable sortable"
! Option !! Description !! Default
|-
| Explosions damage instantly || Explosions cause damage immediately rather than with a delay || ON
|-
| X-Com 1 (UFO) Damage model (0-200%) || Uses the ''[[X-COM|UFO: Enemy Unknown]]'' damage randomization model (0-200% of base damage) instead of Apocalypse's model || OFF
|-
| Gravlift sounds || Sound effects play when units enter or exit gravlifts || ON
|-
| Throwing requires proper facing and pose || Units must face the target and be in the correct stance before throwing || ON
|-
| Ammunition explodes when blown up || Carried ammunition detonates when a unit or vehicle is destroyed || ON
|-
| Display unit paths in battle || Movement paths are visually displayed during tactical combat || ON
|-
| Display additional unit icons (fatal, psi) || Extra status icons shown for fatal wounds and psionic effects || ON
|-
| Allow force-firing parallel to the ground || Force-fire mode allows shots aimed parallel to the ground plane || ON
|-
| Require LOS to maintain psi attack || Psionic attacks require maintained line of sight to the target || OFF
|-
| Hitting vehicle shield produces alternate sound || Different sound effect when vehicle shields absorb damage || ON
|-
| All units run and kneel by default || Units default to running movement and kneeling stance || ON
|-
| Automatically reload weapons when empty || Weapons auto-reload from carried ammunition when a clip is expended || ON
|-
| Weapons autoreload only same ammo type || Auto-reload only uses the same ammunition type that was previously loaded || ON
|-
| Mousewheel changes vertical level in battlescape || Mouse scroll wheel changes the displayed map level || ON
|-
| Select squad with single click || Single-click squad number buttons to select the entire squad || OFF
|-
| Disable scrolling sounds || Turns off the sound effect when scrolling the map || OFF
|}
 
=== General Options ===
 
{| class="wikitable sortable"
! Option !! Description !! Default
|-
| Show debug commands on screen || Displays debug/cheat command buttons in the interface || ON
|-
| Allow unloading clips and quick equip || Advanced inventory controls: Shift+click for auto-equip, Ctrl+click to remove clips || ON
|-
| Enable agent equipment templates || Save and load agent equipment loadouts with number keys (Ctrl+1-0 to save, 1-0 to apply) || ON
|-
| Seed RNG on game start || Seeds the random number generator at game start for varied gameplay || ON
|-
| Enable mouse capture for the window || Captures the mouse cursor within the game window || OFF
|}
 
=== Mod Options ===
 
{| class="wikitable sortable"
! Option !! Description !! Default
|-
| Max tile repair per night || Maximum number of scenery tiles construction vehicles repair each night (0-100) || 5
|-
| Scenery repair cost factor || Percentage of original price organizations pay for scenery repair (0-100%) || 10%
|-
| Stunning hurts relationships || Stunning units belonging to an organization damages X-COM's relationship with them || OFF
|-
| Initiating raid hurts relationships || Starting a raid on a building damages the relationship with its owner || OFF
|-
| (MOD) Original Brainsucker Launcher SFX || Uses the original game's Brainsucker Launcher sound effect || ON
|-
| (MOD) Invulnerable roads || Roads cannot be damaged or destroyed || OFF
|-
| (MOD) Griffon becomes All-Terrain || The Griffon AFV becomes an all-terrain vehicle capable of off-road movement || ON
|-
| (MOD) Wolfhound APC becomes All-Terrain || The Wolfhound APC becomes an all-terrain vehicle || ON
|-
| Vehicles crash on low HP || Vehicles crash when their health drops critically low (weapons and modules may be lost) || OFF
|}
 
=== Cheat Options ===
 
OpenApoc provides a dedicated cheat menu not present in the original game:
 
{| class="wikitable"
! Option !! Description !! Default
|-
| Infinite ammo || Unlimited ammunition for all X-COM agents and vehicles || OFF
|-
| Damage inflicted multiplier || Multiplier for damage dealt by X-COM (0x - 5x) || 1.0x
|-
| Damage received multiplier || Multiplier for damage taken by X-COM (0x - 5x) || 1.0x
|-
| Hostiles multiplier || Multiplier for the number of hostile units spawned (0.5x - 3x) || 1.0x
|-
| Stat growth multiplier || Multiplier for agent stat growth rate (0x - 99.5x) || 1.0x
|}
 
Additional cheat buttons: Give All Research, Make All Orgs Friendly/Hostile, Make All Orgs Utopia/Chaos, Modify Funds, Set Time Before Midnight, Fast Forward to End of Day/Week/Month.
 
== Improved Controls ==
 
The original game's city controls were inconsistent and limited. OpenApoc introduces a completely new control scheme using modifier keys. This can be disabled via the "Improved city control scheme" option to restore vanilla behavior.
 
=== Cityscape Mouse Controls ===
 
{| class="wikitable"
! Input !! Action
|-
| Left Click on building || Open building screen (base screen if building contains a base)
|-
| Right Click on building || Open building screen
|-
| Shift + Left Click || Order attack vehicle
|-
| Shift + Right Click || Order follow vehicle / go to location
|-
| Alt + Shift + Left Click || Order attack building
|-
| Alt + Shift + Right Click || Order go to building
|-
| Alt + Left Click || Open UFOpaedia for object (vehicle type, building function, projectile source)
|-
| Alt + Right Click || Open UFOpaedia for object's owner
|-
| Ctrl + move order (agents) || Force agents to move on foot (never call taxi), allows personal teleporter use
|-
| Ctrl + move order (vehicles) || Allows manual use of city teleporters
|-
| Ctrl + attack order || Forces vehicles to attack target (instead of UFO recovery or escort)
|-
| Ctrl + Left Click (selection) || Add unit/vehicle to selection (additive selection)
|-
| Right Click (selection) || Remove unit/vehicle from selection
|-
| Middle Click || Move camera to location
|}
 
=== Cityscape Mouse on Vehicle/Agent Icons ===
 
{| class="wikitable"
! Input !! Action
|-
| Shift + Right Click || Open location screen
|-
| Ctrl + Shift + Right Click || Open equipment screen
|-
| Alt + Shift + Right Click || Open equipment screen
|}
 
=== Agent Equipment Controls ===
 
{| class="wikitable"
! Input !! Action
|-
| Shift + Click || Auto-equip item to first available slot, or auto-remove to stores/ground
|-
| Ctrl + Click on weapon || Remove clip from weapon
|-
| 1-0 || Apply saved equipment template to all selected agents
|-
| Ctrl + 1-0 || Save current agent's equipment set as a template
|}
 
=== Battlescape Mouse Controls ===
 
{| class="wikitable"
! Input !! Action
|-
| Left Click || Order unit to execute action (move/throw/psi/teleport), open probed unit screen, use item
|-
| Right Click || Turn towards cursor, focus enemy (real-time), use item auto-function (e.g., prime grenade for impact)
|-
| Shift + Left Click || Force-fire at target tile, shot parallel to ground
|-
| Shift + Alt + Left Click || Force-fire at target tile, shot aimed at tile's ground
|-
| Alt + move order || Unit keeps facing target while moving (strafe/backpedal)
|-
| Ctrl + Left Click || Add unit to selection (additive)
|-
| Right Click || Remove unit from selection
|}
 
=== Battlescape Keyboard ===
 
{| class="wikitable"
! Key !! Action
|-
| PgUp / PgDown || Change map levels
|-
| V || Toggle layering
|-
| F2-F4 || Movement modes: Prone / Walk / Run
|-
| F5-F8 || Fire modes: Cease / Aimed / Snap / Auto
|-
| F9-F11 || Behavior: Evasive / Normal / Aggressive
|-
| Backspace || Toggle kneel
|-
| 1-6 || Select squad
|-
| Shift + 1-6 || Select specific unit in current squad
|-
| Shift + Ctrl + 1-6 || Add unit to selection
|-
| Alt + 1-6 || Cycle through spotted enemies of unit
|-
| Enter || Open inventory
|-
| [ / ] || Throw right / left hand item
|-
| ' / \ || Drop right / left hand item
|-
| E || End turn (turn-based mode)
|-
| J || Make unit jump (down from a cliff)
|-
| S / L || Open save / load menu
|}
 
=== General Controls ===
 
{| class="wikitable"
! Key !! Action
|-
| Mousewheel || Scroll lists
|-
| Esc || Go back, close form, cancel
|-
| Enter || Confirm, go forward
|-
| Space || Pause/Resume time
|-
| Tab || Toggle map
|-
| C || Toggle follow mode
|-
| M || Show message log
|-
| Home || Zoom to last event
|-
| Arrows || Move camera
|-
| 0-5 (Cityscape) || Control game speed
|}
 
== Pause Notifications ==
 
OpenApoc adds a comprehensive '''configurable notification system''' that can pause the game when specific events occur. Each notification can be individually toggled. These are not present in the original game.
 
=== City Notifications ===
* UFO spotted
* Vehicle damage (light / moderate / heavy / destroyed)
* Vehicle escaping (damaged and returning to base)
* Vehicle out of ammo
* Vehicle low on fuel
* Agent died
* Agent arrived at base
* Cargo / Transfer / Recovery arrived at base
* Vehicle repaired / rearmed / refuelled
* Not enough ammo / fuel
* Unauthorized vehicle detected
* X-COM base destroyed
 
=== Battle Notifications ===
* Hostile spotted / died
* Unknown unit died
* Agent died / brainsucked
* Agent critically wounded / badly injured / injured
* Agent under fire
* Agent unconscious / left combat zone
* Agent frozen / berserk / panicked / panic over
* Psionic attack on unit / unit under psionic control / freed from control
 
== Original Game Bugs Fixed ==
 
OpenApoc fixes or avoids several [[Known Bugs (Apocalypse)|known bugs]] from the original game:
 
* '''UFO speed bug''': Fixed alien craft having 0 speed in certain conditions
* '''Infiltration screen overflow''': Fixed infiltration screen going blank when exceeding 42 days
* '''Security Station turrets''' (partial): In the original turn-based mode, Security Station turrets did not have their TUs refreshed at the start of turns, rendering them mostly useless after the first shot
* '''Sound issues''': Fixed OGG Vorbis music playback issues that could occur in the original
* '''Learning AI''': The original game's advertised "learning AI" was effectively non-functional — it stopped working after saving the game and depended on specific CD-ROM file locations. OpenApoc does not attempt to replicate this broken feature
* '''Brainsucker Pod handling''': Various fixes for Brainsucker Pod inventory issues, storage space, and alien containment display
 
== Modding Support ==
 
Unlike the original game, OpenApoc is designed with modding in mind:
 
* '''XML data files''': Nearly all game data (units, weapons, vehicles, buildings, organizations) is defined in editable XML files
* '''Mod loading system''': Mods are loaded from a configurable directory (default: <code>./data/mods</code>), specified as a colon-separated list
* '''Lua scripting''': A Lua scripting system allows custom AI and game logic modifications. Scripts are loaded via the <code>OpenApoc.Mod.ScriptsList</code> configuration option
* '''Editable save games''': Since saves are XML in ZIP archives, game state can be manually edited
 
== Features Not Yet Implemented ==
 
As of early 2026, OpenApoc is in '''alpha''' state. The following features from the original game are not yet fully implemented:
 
=== Core Gameplay ===
* Victory and defeat screens
* Alien Takeover screen
* Full organization diplomacy with dual relationship values (the original tracked two separate relationship scores per organization)
* Overspawn mechanic
* Full dynamic action music structure
* Agent name generator
 
=== AI and Movement ===
* Advanced battle AI: cover usage, flanking, grenade throwing, retreat and regrouping behaviors
* Intelligent alien movement patterns within the city
* True ground vehicle movement with lanes, highways, and overtaking behavior
* Evasive/Normal/Aggressive unit AI behavior modes (buttons exist but AI differentiation is incomplete)
 
=== Other ===
* Proper portal locations in the Alien Dimension
* Full graphs and statistics feedback screens
* Organization vehicle AI (buying, selling, managing their own fleets)
* Coloured text support in some UI elements
 
For the full development roadmap, see the [https://github.com/OpenApoc/OpenApoc/issues/263 Playable Alpha], [https://github.com/OpenApoc/OpenApoc/issues/264 Beta], and [https://github.com/OpenApoc/OpenApoc/issues/265 Release 1.0] milestone issues on GitHub.
 
== Debug Mode ==
 
OpenApoc includes an extensive debug system not present in the original game. Debug hotkeys are toggled with '''F1''' in both the cityscape and battlescape. When enabled, various diagnostic and cheat functions become available:
 
=== Cityscape Debug ===
* Ctrl+Alt+Shift+Click: Destroy scenery / collapse building
* Spawn UFOs, repair scenery, warp to alien dimension
* Display road pathfinding, walk modes, alien positions, vehicle paths
* Dump voxel maps for line of sight/fire analysis
* Highlight tubes, roads, and hills with directional filters
 
=== Battlescape Debug ===
* Teleport units, stun/remove units, restore stats
* Reveal entire map with line-of-sight visualization
* Modify morale and psionic stats
* Spawn explosions and directional shots
* Re-link support lines for map parts
 
=== Base Screen Debug ===
* Instantly finish all facility construction
* Near-instantly complete research projects
 
== See Also ==
 
* [[OpenApoc]] — main OpenApoc page
* [[Apocalypse]] — original X-COM: Apocalypse game page
* [[Known Bugs (Apocalypse)]] — bugs in the original game
* [https://github.com/ayrtondenner/OpenApoc-wiki/blob/master/comparison/differences.md OpenApoc Wiki: Differences] &mdash; Extended comparison documentation
* [https://github.com/OpenApoc/OpenApoc OpenApoc on GitHub] — source code and issue tracker
* [https://github.com/OpenApoc/OpenApoc/blob/master/README_HOTKEYS.txt README_HOTKEYS.txt] — complete hotkey reference


[[Category:OpenApoc]]
[[Category:OpenApoc]]

Latest revision as of 21:59, 1 March 2026

OpenApoc is an open-source C++17 reimplementation of X-COM: Apocalypse (1997). While aiming to faithfully recreate the original game, OpenApoc introduces many improvements, bug fixes, and new features. All new gameplay features are optional and can be toggled through the More Options menu.

This page documents the known differences between OpenApoc and the original game. For general OpenApoc information, see the OpenApoc main page.

Technical Improvements

OpenApoc runs natively on modern hardware and operating systems, removing the need for DOS emulation:

  • Platform support: Windows (MSVC 2019+), Linux (GCC 8+/Clang 7+), and macOS (including Apple Silicon)
  • Modern resolutions: Supports any screen resolution and display scaling, with windowed, fullscreen, and borderless modes
  • Performance: Runs at 60 FPS with OpenGL 2.0+ / GLES 3.0 rendering
  • Human-readable save games: Game state is stored as XML in ZIP archives, editable with any text editor
  • Mod support: Full modding via XML data files, Lua scripting, and a configurable mod loading system
  • Multi-monitor support: Can be placed on any display in multi-monitor setups
  • Configurable audio: Separate volume controls for music and sound effects

New Gameplay Options

All new gameplay features are accessible through the More Options menu and can be individually enabled or disabled. Default values are listed — ON means the feature is enabled by default in OpenApoc.

Cityscape Options

Option Description Default
Improved city control scheme Completely new control scheme with modifier keys (see Improved Controls section). Can be disabled to restore vanilla controls. ON
Ferry checks relationship when buying Transtellar checks its relationship with X-COM before providing transport services ON
Allow manual use of teleporters in city Players can manually route vehicles through teleporter buildings for quick transport ON
Allow manual ferrying of cargo and non-combatants Manual control over ferry transport of cargo and non-combat personnel ON
Allow soldiers to call taxi Soldiers can use taxis for transport (restricted to civilians in the original) ON
Allow attacking owned vehicles Allows X-COM to attack its own vehicles (impossible in the original game) ON
Call existing transport instead of spawning them Reuses existing transport vehicles instead of spawning new ones ON
Attempt to recover agent equipment dropped in city Equipment dropped by agents in the city is automatically recovered ON
Enforce vehicle cargo limits Strict enforcement of vehicle cargo capacity OFF
Allow nearby vehicles to pick up loot Nearby X-COM vehicles can collect loot from crash sites ON
Allow loot to be stashed in the building Recovered loot can be deposited in buildings ON
Armored roads Roads have damage reduction, making them harder to destroy ON
Unsupported ground vehicles crash Ground vehicles without road support will crash (weapons and modules may be lost) ON
Vehicles crash when entering dimension gates Vehicles incapable of dimensional travel crash when entering gates ON
Vehicles crash when out of fuel Vehicles crash when their fuel runs out ON
Successful raid collapses building Buildings collapse after a successful raid OFF
Any hit on hostile building provokes retaliation Stray shots hitting hostile buildings trigger retaliation OFF
Put market stock on the right side Market stock displayed on the right side of the transaction screen ON
Left clicking icon opens equip menu Left-clicking a unit's icon opens the equipment screen OFF
Skip turbo movement calculations Performance optimization that skips turbo movement math OFF
Allow ATVs to initiate UFO recovery missions All Terrain Vehicles can start UFO recovery missions ON
Show vehicles in current dimension only Vehicle list filters to show only the current dimension ON
Add prefix to non-X-COM vehicles Non-X-COM vehicles are prefixed with * in vehicle lists for easy identification ON
Don't follow vehicles in strategy view Disables automatic camera following in strategy (isometric) view OFF
Use currency formatting Monetary values displayed with currency formatting (e.g., $1,234,567) ON

Other Cityscape differences:

  • Aircraft weapons may be unequipped (not possible in the original game)

Battlescape Options

Option Description Default
Explosions damage instantly Explosions cause damage immediately rather than with a delay ON
X-Com 1 (UFO) Damage model (0-200%) Uses the UFO: Enemy Unknown damage randomization model (0-200% of base damage) instead of Apocalypse's model OFF
Gravlift sounds Sound effects play when units enter or exit gravlifts ON
Throwing requires proper facing and pose Units must face the target and be in the correct stance before throwing ON
Ammunition explodes when blown up Carried ammunition detonates when a unit or vehicle is destroyed ON
Display unit paths in battle Movement paths are visually displayed during tactical combat ON
Display additional unit icons (fatal, psi) Extra status icons shown for fatal wounds and psionic effects ON
Allow force-firing parallel to the ground Force-fire mode allows shots aimed parallel to the ground plane ON
Require LOS to maintain psi attack Psionic attacks require maintained line of sight to the target OFF
Hitting vehicle shield produces alternate sound Different sound effect when vehicle shields absorb damage ON
All units run and kneel by default Units default to running movement and kneeling stance ON
Automatically reload weapons when empty Weapons auto-reload from carried ammunition when a clip is expended ON
Weapons autoreload only same ammo type Auto-reload only uses the same ammunition type that was previously loaded ON
Mousewheel changes vertical level in battlescape Mouse scroll wheel changes the displayed map level ON
Select squad with single click Single-click squad number buttons to select the entire squad OFF
Disable scrolling sounds Turns off the sound effect when scrolling the map OFF

General Options

Option Description Default
Show debug commands on screen Displays debug/cheat command buttons in the interface ON
Allow unloading clips and quick equip Advanced inventory controls: Shift+click for auto-equip, Ctrl+click to remove clips ON
Enable agent equipment templates Save and load agent equipment loadouts with number keys (Ctrl+1-0 to save, 1-0 to apply) ON
Seed RNG on game start Seeds the random number generator at game start for varied gameplay ON
Enable mouse capture for the window Captures the mouse cursor within the game window OFF

Mod Options

Option Description Default
Max tile repair per night Maximum number of scenery tiles construction vehicles repair each night (0-100) 5
Scenery repair cost factor Percentage of original price organizations pay for scenery repair (0-100%) 10%
Stunning hurts relationships Stunning units belonging to an organization damages X-COM's relationship with them OFF
Initiating raid hurts relationships Starting a raid on a building damages the relationship with its owner OFF
(MOD) Original Brainsucker Launcher SFX Uses the original game's Brainsucker Launcher sound effect ON
(MOD) Invulnerable roads Roads cannot be damaged or destroyed OFF
(MOD) Griffon becomes All-Terrain The Griffon AFV becomes an all-terrain vehicle capable of off-road movement ON
(MOD) Wolfhound APC becomes All-Terrain The Wolfhound APC becomes an all-terrain vehicle ON
Vehicles crash on low HP Vehicles crash when their health drops critically low (weapons and modules may be lost) OFF

Cheat Options

OpenApoc provides a dedicated cheat menu not present in the original game:

Option Description Default
Infinite ammo Unlimited ammunition for all X-COM agents and vehicles OFF
Damage inflicted multiplier Multiplier for damage dealt by X-COM (0x - 5x) 1.0x
Damage received multiplier Multiplier for damage taken by X-COM (0x - 5x) 1.0x
Hostiles multiplier Multiplier for the number of hostile units spawned (0.5x - 3x) 1.0x
Stat growth multiplier Multiplier for agent stat growth rate (0x - 99.5x) 1.0x

Additional cheat buttons: Give All Research, Make All Orgs Friendly/Hostile, Make All Orgs Utopia/Chaos, Modify Funds, Set Time Before Midnight, Fast Forward to End of Day/Week/Month.

Improved Controls

The original game's city controls were inconsistent and limited. OpenApoc introduces a completely new control scheme using modifier keys. This can be disabled via the "Improved city control scheme" option to restore vanilla behavior.

Cityscape Mouse Controls

Input Action
Left Click on building Open building screen (base screen if building contains a base)
Right Click on building Open building screen
Shift + Left Click Order attack vehicle
Shift + Right Click Order follow vehicle / go to location
Alt + Shift + Left Click Order attack building
Alt + Shift + Right Click Order go to building
Alt + Left Click Open UFOpaedia for object (vehicle type, building function, projectile source)
Alt + Right Click Open UFOpaedia for object's owner
Ctrl + move order (agents) Force agents to move on foot (never call taxi), allows personal teleporter use
Ctrl + move order (vehicles) Allows manual use of city teleporters
Ctrl + attack order Forces vehicles to attack target (instead of UFO recovery or escort)
Ctrl + Left Click (selection) Add unit/vehicle to selection (additive selection)
Right Click (selection) Remove unit/vehicle from selection
Middle Click Move camera to location

Cityscape Mouse on Vehicle/Agent Icons

Input Action
Shift + Right Click Open location screen
Ctrl + Shift + Right Click Open equipment screen
Alt + Shift + Right Click Open equipment screen

Agent Equipment Controls

Input Action
Shift + Click Auto-equip item to first available slot, or auto-remove to stores/ground
Ctrl + Click on weapon Remove clip from weapon
1-0 Apply saved equipment template to all selected agents
Ctrl + 1-0 Save current agent's equipment set as a template

Battlescape Mouse Controls

Input Action
Left Click Order unit to execute action (move/throw/psi/teleport), open probed unit screen, use item
Right Click Turn towards cursor, focus enemy (real-time), use item auto-function (e.g., prime grenade for impact)
Shift + Left Click Force-fire at target tile, shot parallel to ground
Shift + Alt + Left Click Force-fire at target tile, shot aimed at tile's ground
Alt + move order Unit keeps facing target while moving (strafe/backpedal)
Ctrl + Left Click Add unit to selection (additive)
Right Click Remove unit from selection

Battlescape Keyboard

Key Action
PgUp / PgDown Change map levels
V Toggle layering
F2-F4 Movement modes: Prone / Walk / Run
F5-F8 Fire modes: Cease / Aimed / Snap / Auto
F9-F11 Behavior: Evasive / Normal / Aggressive
Backspace Toggle kneel
1-6 Select squad
Shift + 1-6 Select specific unit in current squad
Shift + Ctrl + 1-6 Add unit to selection
Alt + 1-6 Cycle through spotted enemies of unit
Enter Open inventory
[ / ] Throw right / left hand item
' / \ Drop right / left hand item
E End turn (turn-based mode)
J Make unit jump (down from a cliff)
S / L Open save / load menu

General Controls

Key Action
Mousewheel Scroll lists
Esc Go back, close form, cancel
Enter Confirm, go forward
Space Pause/Resume time
Tab Toggle map
C Toggle follow mode
M Show message log
Home Zoom to last event
Arrows Move camera
0-5 (Cityscape) Control game speed

Pause Notifications

OpenApoc adds a comprehensive configurable notification system that can pause the game when specific events occur. Each notification can be individually toggled. These are not present in the original game.

City Notifications

  • UFO spotted
  • Vehicle damage (light / moderate / heavy / destroyed)
  • Vehicle escaping (damaged and returning to base)
  • Vehicle out of ammo
  • Vehicle low on fuel
  • Agent died
  • Agent arrived at base
  • Cargo / Transfer / Recovery arrived at base
  • Vehicle repaired / rearmed / refuelled
  • Not enough ammo / fuel
  • Unauthorized vehicle detected
  • X-COM base destroyed

Battle Notifications

  • Hostile spotted / died
  • Unknown unit died
  • Agent died / brainsucked
  • Agent critically wounded / badly injured / injured
  • Agent under fire
  • Agent unconscious / left combat zone
  • Agent frozen / berserk / panicked / panic over
  • Psionic attack on unit / unit under psionic control / freed from control

Original Game Bugs Fixed

OpenApoc fixes or avoids several known bugs from the original game:

  • UFO speed bug: Fixed alien craft having 0 speed in certain conditions
  • Infiltration screen overflow: Fixed infiltration screen going blank when exceeding 42 days
  • Security Station turrets (partial): In the original turn-based mode, Security Station turrets did not have their TUs refreshed at the start of turns, rendering them mostly useless after the first shot
  • Sound issues: Fixed OGG Vorbis music playback issues that could occur in the original
  • Learning AI: The original game's advertised "learning AI" was effectively non-functional — it stopped working after saving the game and depended on specific CD-ROM file locations. OpenApoc does not attempt to replicate this broken feature
  • Brainsucker Pod handling: Various fixes for Brainsucker Pod inventory issues, storage space, and alien containment display

Modding Support

Unlike the original game, OpenApoc is designed with modding in mind:

  • XML data files: Nearly all game data (units, weapons, vehicles, buildings, organizations) is defined in editable XML files
  • Mod loading system: Mods are loaded from a configurable directory (default: ./data/mods), specified as a colon-separated list
  • Lua scripting: A Lua scripting system allows custom AI and game logic modifications. Scripts are loaded via the OpenApoc.Mod.ScriptsList configuration option
  • Editable save games: Since saves are XML in ZIP archives, game state can be manually edited

Features Not Yet Implemented

As of early 2026, OpenApoc is in alpha state. The following features from the original game are not yet fully implemented:

Core Gameplay

  • Victory and defeat screens
  • Alien Takeover screen
  • Full organization diplomacy with dual relationship values (the original tracked two separate relationship scores per organization)
  • Overspawn mechanic
  • Full dynamic action music structure
  • Agent name generator

AI and Movement

  • Advanced battle AI: cover usage, flanking, grenade throwing, retreat and regrouping behaviors
  • Intelligent alien movement patterns within the city
  • True ground vehicle movement with lanes, highways, and overtaking behavior
  • Evasive/Normal/Aggressive unit AI behavior modes (buttons exist but AI differentiation is incomplete)

Other

  • Proper portal locations in the Alien Dimension
  • Full graphs and statistics feedback screens
  • Organization vehicle AI (buying, selling, managing their own fleets)
  • Coloured text support in some UI elements

For the full development roadmap, see the Playable Alpha, Beta, and Release 1.0 milestone issues on GitHub.

Debug Mode

OpenApoc includes an extensive debug system not present in the original game. Debug hotkeys are toggled with F1 in both the cityscape and battlescape. When enabled, various diagnostic and cheat functions become available:

Cityscape Debug

  • Ctrl+Alt+Shift+Click: Destroy scenery / collapse building
  • Spawn UFOs, repair scenery, warp to alien dimension
  • Display road pathfinding, walk modes, alien positions, vehicle paths
  • Dump voxel maps for line of sight/fire analysis
  • Highlight tubes, roads, and hills with directional filters

Battlescape Debug

  • Teleport units, stun/remove units, restore stats
  • Reveal entire map with line-of-sight visualization
  • Modify morale and psionic stats
  • Spawn explosions and directional shots
  • Re-link support lines for map parts

Base Screen Debug

  • Instantly finish all facility construction
  • Near-instantly complete research projects

See Also

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