Here is the full list of all 27 Slugs and Bugs: Conversion achievements.
Spawn a total of 100 slugs and brain bugs added together in a single game. (Game Mode Only)
The heroines have given birth to all 3 types of Hybrid units in a single game. (Game Mode Only)
Convert 20 humans into Thirsters using a Flyer unit in a single game.
Survive for 100 days on Game Mode in a single game.
Convert Evelyn Addams completely.
Convert Chieko Naru completely.
Convert Trixie Goodwin completely.
Convert Absinthe Van Gothen completely.
Convert Amelia Williams completely.
Convert Justine Day completely.
Convert Rose Riley completely.
Fully convert one of the trapped heroines into an infectulon.
Convert a total of 100 humans in the Battle Phase in a single game.
Survive for 50 days on Game Mode in a single game.
Any heroine gives birth to a Hybrid unit in Game Mode.
Congratulations, It's a... Slugger!
Convert Doctor Janice Reeves completely.
Convert 20 humans into Bitten using a Biter unit in a single game.
Convert all the women to Infectulons, completing the Story Content.
Convert 20 humans into Cloned using a Clone unit in a single game.
Beat Game Mode on Easy at Normal or Slow speed.
Beat Game Mode on Normal at Normal or Slow speed.
Beat Game Mode on Hard at Normal or Slow speed.
Unlock all the scenes in the Memory Chamber in a single game.
Unlock ALL achievements.
Unlock ALL the Bad Ends in the memory Chamber in a single game.
Have a Slug get the killing blow or conversion on a Tank unit in Game Mode.