UFO Incursions (Apocalypse)
Alien Craft Type and Quantity Appearing in Mega-Primus
In General
Aliens send their craft through a 'portal', called a Dimension Gate, appearing at random locations and random positions within the cityscape as time progresses. It is an invunerable device.
Alien Craft Growth Limits
UFOs are 'grown' in the Alien Dimension at the start of the week of only a certain quantity and type dependant on the number of weeks elasped in the game:
Maximum UFO Quantity
| Week |  |
 |
 |
 |
 |
 |
 |
 |
 |
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|---|---|---|---|---|---|---|---|---|---|---|
| 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 |
Alien Mission: Schedule
At the start of each week (Monday), the Aliens randomly choose days and times within this new week to perform a variety mission types: Infiltration, Search, Bombing, Overspawn Drop. When a mission is due according to Monday's timetable, the aliens will choose a mission style dependant on importance (the percentage chance) and the number of weeks elasped in the game:
Mission Schedules
| Week | Infiltration | Search | Bombing | 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% |
Once a mission is selected, the aliens will allocate the UFOs required (if available) in the Alien Dimension to immediately spawn into Mega-Primus.
Note: An Overspawn Drop for Week 7 is an error in the game since the craft needed, a Mothership, is not yet available.
Alien Missions
Any alien mission chosen in the schedule will only commence if the required UFOs are present in the Alien Dimension, that is, the mission will only start if the needed craft are available, and if not, the mission will not start and the 'time and day' mission slot is forfeited.
The alien craft will materialise from the dimension gates in sequence (all Primary craft, all Escort craft, all others) according to their selected mission. When the first craft has spawned in, the next craft due will choose a gate randomly of the three, until all are present. (A save/load between each spawn will again randomise the gate choice for the UFO due to appear next.)
The alien crafts listed in "Escort" are assigned protection duty of the "Primary" group's leader, hence, the first craft that spawned into the city is (always) the leader of all primary craft. If the leader is lost when under escort, the assigned escorts will select the 'second in command' primary craft as the new leader... until all primaries are either shot down or have escaped (from mission objective complete or craft sustained massive damage and aborts objective) back into the gates. If no more (viable) primary craft are present, any escorts remaining will return to the gates and leave. Escorts are assigned escort duty only and will not escort other designated escorts. Primary UFOs will proceed with their mission regardless if an escort is available.
Important: The column "Mission" in the following tables is not based on elapsed weeks but the variety of craft types that may partake in each section's (Infiltration, Search etc.) mission type. The selection of a group will start at the bottom and move upwards through the list (ignoring Week) until the UFOs present in the Alien Dimension can fulfil the particular mission's grouping requirement. If a group cannot be formed, the mission will not proceed.
UFOs in the Bombing column will attack any hostile organisation's buildings.
Infiltration
If Aliens successfully target a building (unknowingly) with an X-Com base, a Base Defence mission wil immediately commence.
Alien crafts used to insert alien lifeforms into buildings:
| Mission | Primary | Escort | Bombing | Week |
|---|---|---|---|---|
| 1 |  |  | 1 | |
| 2 | | | 1 | |
| 3 |  | 2 | ||
| 4 | |  | 2 | |
| 5 | | | 2 | |
| 6 |  | | 4 | |
| 7 |  | | 3 | |
| 8* | | 4 | ||
| 9 | | | 3 | |
| 10 | | | 3 | |
| 11 | | 4 | ||
| 12 | | | 4 | |
| 13 | |  | 5 | |
| 14 | |  | 8 | |
| 15 | | | | 8 |
| 16* |  | | 7 | |
| 17** | | | | 7 |
| 18 | | | 7 | |
| 19 |  | 8 | ||
| 20 | | | 8 |
*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 an error in the allocation of available crafts - instead of checking whether there are two Battleships, it checks whether there is one Battleship twice.
Search
Alien crafts used to search a building for an X-Com base:
| Mission | Primary | Escort | Week |
|---|---|---|---|
| 1 | | 5 | |
| 2 | | 5 | |
| 3 | | 5 | |
| 4 | | 5 | |
| 5 | | 5 | |
| 6 | | 5 | |
| 7 | | 5 | |
| 8 | | 5 | |
| 9 | | | 7 |
| 10 | | | 8 |
- Base Assault fleets can appear from Week 5 onwards.
Important: Once an X-Com base has been located, the "Search" mission style becomes an 'X-Com Base Attack' mission style (and if they are successful by inserting aliens, will become a battlescape Base Defense mission). Any further X-Com Base Attack missions will use only one UFO; the first primary craft in the "Search" table is only used (and maybe some escorting craft) since the aliens don't need to search so many buildings now, they don't need to use so many craft!
Aliens that have located an X-Com base will cease searching for bases until their target is destroyed.
Bombing Buildings
Alien craft groups assigned for building destruction, using gun and bombs, of hostile organisations in Mega-Primus.
| Mission | Primary | Escort | Week |
|---|---|---|---|
| 1 | | 4 | |
| 2 | | | 4 |
| 3 | | 5 | |
| 4 | | | 4 |
| 5 | | | 5 |
| 6 | | 6 | |
| 7 | | | 7 |
| 8 | | 9 | |
| 9 | | 9 | |
| 10 | | 8 |
- Bombing fleets appear from Week 4 onwards.
Overspawn Drops
A mission style which always contains a Mothership as the primary leader to randomly 'unload' an Overspawn terror unit into Mega-Primus. Escort assigned craft may also attack buildings at random as with the craft listed in Bombing.
| Mission | Primary | Escort | Bombing | Week |
|---|---|---|---|---|
| 1 | | 8 | ||
| 2 | | | 8 | |
| 3 | | | | 8 |
| 4 | | | 8 | |
| 5 | | | 11 |
- Overspawn drops can appear from Week 8 onwards.
- A fleet with two Motherships is guaranteed to be on an Overspawn Drop mission.
Apcoalypse Mission
A special version of a Bombing mission which only happens once, once the Control Chamber in the alien dimension is destroyed. The next alien mission that is time-tabled wiil be the Apocalypse Mission in which all remaining UFOs in the Alien Dimension (except Probes) will swarm out of the Dimension Gates and proceed to demolish Mega-Primus!