Alien Appearance Ratios
| December (1998) - January | |||||
|---|---|---|---|---|---|
| Mission/Race | Sectoid | Snakeman | Ethereal | Muton | Floater |
| Alien Research | 70% | 10% | - | - | 20% |
| Alien Harvest | 50% | 20% | - | - | 30% |
| Alien Abduction | 60% | - | - | - | 40% |
| Alien Infiltration | 60% | 20% | - | - | 20% |
| Alien Base | 30% | 20% | - | - | 50% |
| Alien Terror | 30% | - | - | - | 70% |
| Alien Retaliation | 60% | 20% | - | - | 20% |
| February - March | |||||
|---|---|---|---|---|---|
| Mission/Race | Sectoid | Snakeman | Ethereal | Muton | Floater |
| Alien Research | 60% | 10% | - | - | 30% |
| Alien Harvest | 50% | - | - | - | 50% |
| Alien Abduction | 40% | - | - | - | 60% |
| Alien Infiltration | 50% | 20% | - | - | 30% |
| Alien Base | 40% | 20% | - | - | 40% |
| Alien Terror | 60% | - | - | - | 40% |
| Alien Retaliation | 30% | 30% | - | - | 40% |
| April - May | |||||
|---|---|---|---|---|---|
| Mission/Race | Sectoid | Snakeman | Ethereal | Muton | Floater |
| Alien Research | 30% | 10% | - | 30% | 30% |
| Alien Harvest | 30% | - | - | 30% | 40% |
| Alien Abduction | 50% | - | - | - | 50% |
| Alien Infiltration | 20% | 20% | - | 50% | 10% |
| Alien Base | 10% | 40% | - | 30% | 20% |
| Alien Terror | 20% | 60% | - | - | 20% |
| Alien Retaliation | 20% | 20% | - | 40% | 20% |
| June - July | |||||
|---|---|---|---|---|---|
| Mission/Race | Sectoid | Snakeman | Ethereal | Muton | Floater |
| Alien Research | 20% | 10% | - | 40% | 30% |
| Alien Harvest | 10% | - | - | 40% | 50% |
| Alien Abduction | 30% | - | - | - | 70% |
| Alien Infiltration | 10% | 10% | 40% | 30% | 10% |
| Alien Base | 10% | 40% | 10% | 20% | 20% |
| Alien Terror | 10% | 20% | 40% | 20% | 10% |
| Alien Retaliation | 20% | 20% | 20% | 20% | 20% |
| August and Beyond | |||||
|---|---|---|---|---|---|
| Mission/Race | Sectoid | Snakeman | Ethereal | Muton | Floater |
| Alien Research | 30% | 10% | - | 30% | 30% |
| Alien Harvest | 30% | - | - | 30% | 40% |
| Alien Abduction | 50% | - | - | - | 50% |
| Alien Infiltration | 20% | 20% | 10% | 40% | 10% |
| Alien Base | 10% | 20% | 40% | 20% | 10% |
| Alien Terror | 20% | 30% | 20% | 20% | 10% |
| Alien Retaliation | 10% | 10% | 40% | 20% | 20% |
Notes
- The first appearance rate block includes December 1998, however the game starts in January 1999. It is included because the tables cover 2 month blocks.
- All months beyond August 1999 use the August table.
- All values listed above are interpreted off probability tables obtained directly from GEOSCAPE.EXE.
- The crew of already established Alien Bases, ships on Alien Supply missions, and Terror Sites will be crewed by the same crew that founded the base or terror site, and are not affected by these tables.
- The Cydonia mission has a pre-defined crew setup.
See also
 X-COM: Enemy Unknown/UFO Defense
| |
| X-COM | Soldiers • Heavy Weapons Platforms |
| Aliens: | Floater • Sectoid • Snakeman • Ethereal • Muton Terror Units: Reaper • Cyberdisc • Chryssalid • Zombie • Sectopod • Celatid • Silacoid |
| Stats | Time Units • Energy (Stamina) • Health • Bravery • Reactions • Firing Accuracy • Throwing Accuracy • Strength • Psionic Strength • Psionic Skill • Melee Accuracy • Stun • Morale • Rank • Fatal Wounds |
| Data | Alien Stats • Damage Modifiers • Alien Appearance Ratios • Alien Weapon Loadouts |