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