Alien Appearance Ratios (TFTD)
|December (2039) - January|
|Alien Probe Mission||70%||30%||-||-||-|
|Alien Resource Raid||60%||40%||-||-||-|
|Alien Colony Expansion||30%||70%||-||-||-|
|Alien Surface Attacks||-||100%||-||-||-|
|Floating Base Attack||60%||40%||-||-||-|
|February - March|
|Alien Probe Mission||60%||30%||10%||-||-|
|Alien Resource Raid||40%||60%||-||-||-|
|Alien Colony Expansion||40%||40%||20%||-||-|
|Alien Surface Attacks||20%||80%||-||-||-|
|Floating Base Attack||30%||40%||30%||-||-|
|April - May|
|Alien Probe Mission||30%||40%||30%||-||-|
|Alien Resource Raid||50%||50%||-||-||-|
|Alien Colony Expansion||10%||30%||60%||-||-|
|Alien Surface Attacks||20%||30%||50%||-||-|
|Floating Base Attack||20%||60%||20%||-||-|
|June - July|
|Alien Probe Mission||20%||10%||40%||30%||-|
|Alien Resource Raid||30%||-||-||70%||-|
|Alien Colony Expansion||10%||40%||30%||20%||-|
|Alien Surface Attacks||10%||30%||20%||20%||20%|
|Floating Base Attack||20%||30%||30%||20%||-|
|August and Beyond|
|Alien Probe Mission||20%||20%||20%||40%||-|
|Alien Resource Raid||50%||-||-||50%||-|
|Alien Colony Expansion||10%||20%||60%||10%||-|
|Alien Surface Attacks||20%||20%||20%||10%||30%|
|Floating Base Attack||10%||10%||60%||20%||-|
- December 2039 is included in the first table, but the game begins in January 2040. Each table covers two month blocks.
- All months beyond August 2040 use the August table.
- All values listed above are interpreted off probability tables obtained directly from TFTD's GEOSCAPE.EXE.
- Established Alien Colonies, Artefact Sites and the final mission T'leth have fixed crew types.
- Alien subs on Colony Supply Missions will be crewed by the same species that established the Colony, and ignore the monthly tables.
- Alien Surface Attacks missions may be of several types, with these frequencies:
|Month||Port/Island Attack||Shipping Lane||Artefact|
|June and beyond||20%||30%||50%|
|After 12th Artefact||40%||60%||0%|
- Port/Island Attack Alien Surface Attacks missions behave like the ordinary Alien Terror alien mission in UFO: Enemy Unknown. A series of scout subs will be sent to an area, followed by a Battleship that will touch down at a port city or island to create a terror site. Responding to such a site starts a Port Attack or Island Attack mission similar to Terror Missions in UFO, with the accordant bonuses and penalties. Port/Island Attack missions use the appearance ratio values listed for Alien Surface Attacks for the current month.
- Shipping Lane Alien Surface Attacks missions will simply generate a terror site on a shipping route at 00:30 on the first of the month (there is no Alien Submarine activity associated with this type, and the site's appearance hence cannot be avoided by any means). Responding to such a site starts a Shipping Lane Mission, in which X-Com must rid a cruise or cargo ship of alien infestation. These are two-part missions, taking place on two long and narrow maps representing the upper and lower decks of the ship; however, they otherwise score as normal for a Terror Mission (including the -1000 penalty for not responding). Shipping Lane Missions will use the appearance ratio values listed for Alien Surface Attacks for June and July (no matter what month it actually is), which enables "early" appearances of Tasoths since these missions appear from April onward.
- Artefact Alien Surface Attacks missions will generate an "artefact site" at a deep-sea location (not the surface) at 00:30 on the first of the month (again, there is no associated Alien Submarine activity and the site's generation cannot be avoided). These sites represent the twelve communications relays mentioned in Alien Origins. These missions are also two-part; the first map is a pyramid hunt on the seafloor for the relay's location, while the second is a battle within the facility itself to destroy its Synomium Device. As there are no civilians on this type of mission, there are different point rewards and penalties; destroying the device scores 750 points, while failing to destroy it scores -750 and failing to respond -2000. Artefact Sites are always crewed by Aquatoids and Tasoths accompanied by Hallucinoids and Tentaculats, and ignore these tables.
- As there are only twelve relays, after twelve Artefact Sites have been activated (regardless of the outcome) no more will appear and the aliens will return to attacking surface targets every month. However, as the earliest month possible for the twelfth Artefact Site is May 2041 and it's more likely to occur in 2042, most games will end long before this actually occurs.
- Alien Appearance Ratios - For Enemy Unknown/UFO Defense
|Terror From The Deep|
|Aliens:||Aquatoid • Gillman • Lobster Man • Tasoth • Mixed Crew|
|Terror Units:||Bio-Drone • Calcinite • Deep One • Hallucinoid • Tentaculat • Zombie • Triscene • Xarquid|
|Data:||TFTD Alien Stats • Alien Rank • TFTD Damage Modifiers • TFTD Alien Appearance Ratios|