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