Alien Appearance Ratios (TFTD)

January
Mission/Race	Aquatoid	Gillman	Lobsterman	Tasoth	Mixed Crew
Alien Probe Mission	70%	30%	-	-	-
Alien Interdiction	50%	50%	-	-	-
Alien Resource Raid	60%	40%	-	-	-
Alien Infiltration	60%	40%	-	-	-
Alien Colony Expansion	30%	70%	-	-	-
Alien Surface Attacks	-	100%	-	-	-
Floating Base Attack	60%	40%	-	-	-

February - March
Mission/Race	Aquatoid	Gillman	Lobsterman	Tasoth	Mixed Crew
Alien Probe Mission	60%	30%	10%	-	-
Alien Interdiction	50%	50%	-	-	-
Alien Resource Raid	40%	60%	-	-	-
Alien Infiltration	50%	30%	20%	-	-
Alien Colony Expansion	40%	40%	20%	-	-
Alien Surface Attacks	20%	80%	-	-	-
Floating Base Attack	30%	40%	30%	-	-

April - June
Mission/Race	Aquatoid	Gillman	Lobsterman	Tasoth	Mixed Crew
Alien Probe Mission	30%	40%	30%	-	-
Alien Interdiction	30%	50%	20%	-	-
Alien Resource Raid	50%	50%	-	-	-
Alien Infiltration	20%	50%	30%	-	-
Alien Colony Expansion	10%	30%	60%	-	-
Alien Surface Attacks	20%	30%	50%	-	-
Floating Base Attack	20%	60%	20%	-	-

July - September
Mission/Race	Aquatoid	Gillman	Lobsterman	Tasoth	Mixed Crew
Alien Probe Mission	20%	10%	40%	30%	-
Alien Interdiction	10%	-	40%	50%	-
Alien Resource Raid	30%	-	-	70%	-
Alien Infiltration	10%	30%	20%	40%	-
Alien Colony Expansion	10%	40%	30%	20%	-
Alien Surface Attacks	10%	30%	20%	20%	20%
Floating Base Attack	20%	30%	30%	20%	-

October and Beyond
Mission/Race	Aquatoid	Gillman	Lobsterman	Tasoth	Mixed Crew
Alien Probe Mission	20%	20%	20%	40%	-
Alien Interdiction	30%	-	30%	40%	-
Alien Resource Raid	50%	-	-	50%	-
Alien Infiltration	30%	10%	50%	10%	-
Alien Colony Expansion	10%	20%	60%	10%	-
Alien Surface Attacks	20%	20%	20%	10%	30%
Floating Base Attack	10%	10%	60%	20%	-

Notes

• All months beyond October 2040 use the October table.
• All values listed above are interpreted off probability tables obtained directly from TFTD's GEOSCAPE.EXE.
• Established Alien Colonies and Artefact Sites will always be defended by a Mixed Crew. T'leth has a unique, fixed crew.
• Alien subs on Colony Supply Missions will be crewed by the same species that established the Colony, and ignore the monthly tables.
• "Triggered" Floating Base Attack missions are crewed by the same race as the submarine shot down. "Scheduled" Floating Base Attack missions can be crewed by Aquatoids, Gill Men, Lobster Men or Tasoths (but not Mixed Crew).
• Alien Surface Attacks missions may be of several types, with these frequencies:

Month	Port/Island Attack	Shipping Lane	Artefact
January-March	100%	0%	0%
April-May	40%	60%	0%
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 01:00 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 July to September (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 01:00 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.

See Also

• Alien Appearance Ratios - For Enemy Unknown/UFO Defense