Tactical Combat Missions (Apocalypse)
X-COM: Apocalypse has a variety of different types of Tactical Combat Missions, which take place in the Battlescape. This page details the various kinds of missions that can occur and how they are triggered.
Investigation
This mission type is triggered when you have Agents in a Mega-Primus building and select the "Investigate building" option on the building screen. A mission will only occur if there are in fact aliens in the building; otherwise, you will receive a message informing you of the lack of aliens and a relations penalty with the organisation owning the building due to the unnecessary inconvenience. You will also receive this message if the only aliens in the building are Multiworm Eggs and/or Chrysalides; fortunately, this is rare.
This mission type will take place in a map randomly generated from modules according to the building type. The number of modules used varies with the number of units in play.
Opposition consists of all aliens currently in the building (unit limits permitting). If the owner of the building is hostile to X-COM, you will also face their guards. If the owner is also hostile to the Aliens, a three-way battle will ensue - this may result in the aliens being slaughtered by the guards before X-COM ever locates them.
To win the mission, kill or subdue all opponents. Note that damage to the building will cause a relations penalty. Aliens that escape the combat area during the battle will move to a neighbouring building, as will all remaining aliens if X-COM retreats from the battle.
Raid
This mission type is triggered when you have Agents in a Mega-Primus building and select the "Raid building" option on the building screen. You cannot raid buildings owned by X-COM.
Like an investigation, this mission type will take place in a randomly-generated building map. Unlike an investigation, random items will be placed at certain locations on the map.
Opposition consists of the building owner's guards only. Any aliens in the building will not be present.
To win the mission, kill or subdue all the guards.
Note that the only real purpose of raiding is to acquire money and/or items (via stealing random "loot" items and/or the guards' own equipment). While it will cause the building owner's balance to drop, this doesn't have any significant effects.
UFO Crash Site
If alien craft are shot down in Mega-Primus (by X-COM or, rarely, others), they will usually crash-land. Sending a manned air vehicle to the crash site (with "Go to map point") will initiate an attempt to recover the wreckage. If the craft is a Probe or Scout Ship, this will occur instantly and automatically (as there are no crew). Attempting to recover any larger craft, however, will result in a Tactical Combat Mission.
Note that only air vehicles can perform crash site recoveries, as road vehicles cannot leave the road to reach the crash site. Additionally, only one vehicle can perform the recovery - this is a powerful incentive to keep a Valkyrie Interceptor or Hawk Air Warrior available until hybrid aircraft are developed.
These missions will occur on a special map, with the crashed UFO in the middle and all aliens initially on board. The map is always the same for a given type of UFO, and is not randomised. Opposition consists of the UFO's crew.
To win the mission and recover the UFO, kill or subdue all the aliens. Note that you have only one chance to succeed per UFO; if you retreat from battle, the aliens will blow up their craft (and themselves with it) to avoid capture. This will also happen if you ignore a crash site for more than a few in-game minutes.
Base Attack
The only type of mission X-COM does not initiate, a Base Attack will occur if either a UFO drops aliens directly into an X-COM Base (aliens spreading to a base through the People Tubes must be found through investigation) or if a hostile organization randomly decides to "raid" or "storm" one. Megapol, the three gangs, and any infiltrated organisation are three times as likely to perform a Base Attack compared with other organisations. If there are no X-COM units present at the base whatsoever (even technical personnel), the raid will automatically succeed and destroy the base; otherwise, this will result in a Tactical Combat Mission.
In these missions, you control not only Agents, but also any technical personnel at the base. If there are more than 36 X-COM units at the base, who you get is random - it is unfortunately possible to receive no Agents at all even if there are a couple present. X-COM's units will, however, be assisted by any Security Stations at the base, although the turrets are unfortunately not manually controllable.
Base Attacks will occur inside an X-COM Base itself, with terrain varying depending on what modules you have in the base. Intruders will spawn inside the Access Lift and/or any Vehicle Repair Bays; X-COM units can spawn in any completed module except Vehicle Repair Bays (the Access Lift is not excluded).
To win the mission, kill or subdue all intruders. You will lose the mission, and the base with it, if all your personnel flee the battle or are killed - Security Stations don't count. If you lose your last base this way, you will get a Game Over.
Alien World Incursion
Once X-COM has accessed and explored the Alien Dimension, it is possible to land craft at the alien structures within. Selecting either "Investigate building" or "Raid building" will trigger a mission in which X-COM attempts to destroy the building (there is no difference between the options).
These missions will occur on a large map (3x3 modules). There will be one large module of size 2x2; this will contain the alien forces present at the beginning of the mission. Two of the small modules on the rim of the map will be designated as X-COM spawn locations.
A unique feature of these missions is the orange "pad" terrain features found in the large 2x2 module and two of the "small" modules that are not X-COM spawn locations. At regular intervals, one additional alien will be placed on one of of these pads somewhere on the map. The specific aliens used as reinforcements, and the intervals at which a reinforcement appears, depends on the particular alien structure X-COM is assaulting. The pads can be destroyed only by Vortex Mines or (in the Spawning Chamber) by the Queenspawn's tentacles. No alien will be placed if all the pads have been destroyed, although destroying only some of them will not slow the speed at which they arrive.
To win these missions, all the objects outlined in the Briefing must be destroyed (at which point the message bar will display "Building disabled"). After that, it is necessary to either evacuate all soldiers or kill all remaining aliens (the latter is very difficult if there are still intact reinforcement pads).
To unlock the Alien World Incursion missions, one must first visit the Alien Dimension with any hybrid craft. After that, the Quantum Physics topic The Alien Dimension will appear, which in turn unlocks the first of a series of Biochemistry topics named "Alien building". Completing this topic allows the first Alien World Incursion mission to be performed, which will unlock the next "Alien building" topic, and so on. As such, these ten missions must be done in order.
- Sleeping Chamber
- Food Chamber
- Alien Farm
- Maintenance Factory
- Incubator Chamber
- Control Chamber
- Spawning Chamber
- Organic Factory
- Megapod Chamber
- Dimension Gate Generator
Note that, when one of these missions is completed, the associated structure will collapse on the Alien Dimension Cityscape. Do not launch your craft until the animation is complete, or it will be "destroyed by collapsing building".
As the final alien structure and thus the final mission of the game, there are a few differences between the Dimension Gate Generator and the other nine Alien World Incursion missions. See its page for details.