UFO Incursions (Apocalypse)

From UFOpaedia
Jump to navigation Jump to search

This page lists the various nuts and bolts of how the game decides which Alien Craft come out of the Dimension Gates and what they do once in Mega-Primus.

Unlike in UFO: Enemy Unknown and X-Com: Terror From the Deep, the Aliens in X-COM: Apocalypse do not have infinite reserves of craft. Rather, the pool of craft in the Alien Dimension is tracked, with new UFOs being constructed every Monday (up to a limit) and X-COM interceptions removing craft from the pool.

Every time an alien mission is scheduled, the game rolls randomly on a table to decide what act they will attempt to perform. This table changes every week. Then, once an act has been selected, the specific UFO makeup of the incursion is chosen deterministically from tables for each possible act depending on what craft are available in the Alien Dimension pool; as reproduced here, the tables increase in priority downward, so the aliens will always use the highest-numbered fleet possible for the chosen mission.

Some UFOs on the Infiltration and Overspawn Drop tables are listed as "Bombing" craft. These craft will bomb a building, as though on an Air Raid mission.

Destroying the Control Chamber building permanently halts the production of alien craft. It also triggers a special incursion not found on these tables - the next time an alien mission is scheduled, all remaining UFOs (except Probes) will swarm out of the Dimension Gates and start tearing down Mega-Primus as though on a very large Air Raid mission. This final battle is typically referred to as "the Apocalypse mission".

UFO Production

Week Alien Probe Alien Scout Ship Alien Transporter Alien Fast-Attack Ship Alien Destroyer Alien Assault Ship Alien Bomber Alien Escort Ship Alien Battleship Alien Mothership
1 9 9
2 2 4 3 2
3 2 4 2 2 3
4 1 2 1 1 2 2
5 1 1 1 1 2
6 1 1 1 1 1
7 1 1 1 1 1
8 1 1 1 1 1
9 1 1
10 1 1
11 1 1 1 1
12 1 1
13 1 1 1
14 1 1
15 1
16+ 1 1 1 1
Maximum 15 15 6 6 6 6 6 6 4 2

Mission Chance

Week Infiltration Base Assault Air Raid Overspawn Drop
1-3 100% 0% 0% 0%
4 90% 0% 10% 0%
5-6 80% 10% 10% 0%
7 70% 10% 10% 10%*
8 50% 20% 10% 20%
9-11 40% 20% 20% 20%
12 30% 30% 20% 20%
13 30% 20% 30% 20%
14 40% 20% 20% 20%
15-18 30% 20% 20% 30%
19 20% 20% 30% 30%
20+ 10% 40% 20% 30%

*An Overspawn drop in Week 7 can't actually happen, as there are guaranteed to be no Motherships available (none have spawned yet).

Infiltration Fleets

Mission Primary Escort Bombing Week
1Apoc ufo2 icon.pngApoc ufo2 icon.pngApoc ufo1 icon.png1
2Apoc ufo2 icon.pngApoc ufo2 icon.pngApoc ufo2 icon.pngApoc ufo1 icon.pngApoc ufo1 icon.png1
3Apoc ufo3 icon.pngApoc ufo2 icon.pngApoc ufo2 icon.png2
4Apoc ufo3 icon.pngApoc ufo4 icon.pngApoc ufo4 icon.png2
5Apoc ufo3 icon.pngApoc ufo3 icon.pngApoc ufo4 icon.pngApoc ufo4 icon.png2
6Apoc ufo3 icon.pngApoc ufo5 icon.pngApoc ufo4 icon.pngApoc ufo4 icon.png4
7Apoc ufo6 icon.pngApoc ufo2 icon.pngApoc ufo2 icon.png3
8*Apoc ufo6 icon.pngApoc ufo5 icon.pngApoc ufo5 icon.png4
9Apoc ufo6 icon.pngApoc ufo3 icon.pngApoc ufo2 icon.pngApoc ufo2 icon.pngApoc ufo2 icon.png3
10Apoc ufo6 icon.pngApoc ufo6 icon.pngApoc ufo4 icon.pngApoc ufo4 icon.pngApoc ufo4 icon.png3
11Apoc ufo6 icon.pngApoc ufo5 icon.pngApoc ufo5 icon.png4
12Apoc ufo6 icon.pngApoc ufo6 icon.pngApoc ufo5 icon.pngApoc ufo4 icon.pngApoc ufo4 icon.pngApoc ufo4 icon.png4
13Apoc ufo6 icon.pngApoc ufo6 icon.pngApoc ufo7 icon.pngApoc ufo7 icon.png5
14Apoc ufo6 icon.pngApoc ufo6 icon.pngApoc ufo8 icon.pngApoc ufo8 icon.pngApoc ufo8 icon.png8
15Apoc ufo6 icon.pngApoc ufo6 icon.pngApoc ufo8 icon.pngApoc ufo8 icon.pngApoc ufo8 icon.pngApoc ufo7 icon.pngApoc ufo7 icon.png8
16*Apoc ufo9 icon.pngApoc ufo6 icon.pngApoc ufo6 icon.pngApoc ufo8 icon.pngApoc ufo8 icon.png7
17**Apoc ufo9 icon.pngApoc ufo8 icon.pngApoc ufo9 icon.png7
18Apoc ufo9 icon.pngApoc ufo8 icon.pngApoc ufo8 icon.png7
19Apoc ufo10 icon.png8
20Apoc ufo10 icon.pngApoc ufo9 icon.pngApoc ufo8 icon.pngApoc ufo8 icon.png8


*These fleets will never appear, as the ships required will also fulfil a higher-priority fleet.

**This fleet can appear as long as the aliens have at least one Battleship and one Escort Ship (though two Battleships will still appear in Mega-Primus). This is the result of a bug in the spawn routine; instead of checking whether there are two Battleships, it checks whether there is one Battleship twice.

Base Assault Fleets

Mission Primary Escort Week
1Apoc ufo1 icon.pngApoc ufo1 icon.pngApoc ufo1 icon.png5
2Apoc ufo2 icon.pngApoc ufo2 icon.pngApoc ufo2 icon.pngApoc ufo2 icon.png5
3Apoc ufo2 icon.pngApoc ufo2 icon.pngApoc ufo2 icon.pngApoc ufo1 icon.pngApoc ufo1 icon.pngApoc ufo1 icon.png 5
4Apoc ufo4 icon.pngApoc ufo4 icon.pngApoc ufo2 icon.pngApoc ufo2 icon.pngApoc ufo2 icon.png5
5Apoc ufo5 icon.pngApoc ufo5 icon.pngApoc ufo4 icon.pngApoc ufo4 icon.png5
6Apoc ufo5 icon.pngApoc ufo5 icon.pngApoc ufo4 icon.pngApoc ufo4 icon.pngApoc ufo2 icon.pngApoc ufo2 icon.pngApoc ufo2 icon.png5
7Apoc ufo5 icon.pngApoc ufo5 icon.pngApoc ufo5 icon.pngApoc ufo6 icon.png5
8Apoc ufo7 icon.pngApoc ufo7 icon.pngApoc ufo5 icon.pngApoc ufo5 icon.png5
9Apoc ufo9 icon.pngApoc ufo8 icon.png7
10Apoc ufo10 icon.pngApoc ufo8 icon.png8


  • Subversion fleets can appear from Week 5 onwards.

Air Raid Fleets

Mission Primary Escort Week
1Apoc ufo4 icon.pngApoc ufo4 icon.png4
2Apoc ufo4 icon.pngApoc ufo4 icon.pngApoc ufo4 icon.pngApoc ufo2 icon.pngApoc ufo2 icon.png4
3Apoc ufo5 icon.pngApoc ufo5 icon.pngApoc ufo5 icon.png5
4Apoc ufo5 icon.pngApoc ufo5 icon.pngApoc ufo4 icon.pngApoc ufo4 icon.png4
5Apoc ufo7 icon.pngApoc ufo7 icon.pngApoc ufo4 icon.pngApoc ufo4 icon.pngApoc ufo4 icon.png5
6Apoc ufo7 icon.pngApoc ufo7 icon.pngApoc ufo7 icon.pngApoc ufo5 icon.pngApoc ufo5 icon.png6
7Apoc ufo7 icon.pngApoc ufo7 icon.pngApoc ufo8 icon.pngApoc ufo8 icon.png7
8Apoc ufo9 icon.pngApoc ufo9 icon.pngApoc ufo7 icon.pngApoc ufo7 icon.png9
9Apoc ufo10 icon.pngApoc ufo9 icon.pngApoc ufo9 icon.png9
10Apoc ufo10 icon.pngApoc ufo9 icon.pngApoc ufo7 icon.pngApoc ufo7 icon.png8


  • Attack fleets appear from Week 4 onwards.

Overspawn Drop Fleets

Mission Primary Escort Bombing Week
1Apoc ufo10 icon.png8
2Apoc ufo10 icon.pngApoc ufo8 icon.pngApoc ufo8 icon.png8
3Apoc ufo10 icon.pngApoc ufo8 icon.pngApoc ufo8 icon.pngApoc ufo8 icon.pngApoc ufo7 icon.pngApoc ufo7 icon.png8
4Apoc ufo10 icon.pngApoc ufo9 icon.png8
5Apoc ufo10 icon.pngApoc ufo10 icon.pngApoc ufo9 icon.pngApoc ufo9 icon.png11


  • Overspawn drops can appear from Week 8 onwards.
  • A fleet with two Motherships is guaranteed to be on an Overspawn Drop mission.

See Also