Here is the full list of all 21 Fatal Theory achievements.
Beat Lilith
Max level up Guantlets
Beat Johnny
Max level up Whip
Beat Punchy Mech
Max level up Swords
999+ Hit Combo
Beat Spectre
Beat Giancarlo
Beat Matt & Adam
Max level up Baseball Bat
Max level up Vlad the Impaler
Beat Donatello
Beat Vlad
Start Story Mode
Unlock Umbrella (not the cheat way)
Max level up Umbrella
Max level up Black Blade
Max level up Nick
Beat Arcade
300+ on Survival