Complete game with Ashley
Complete game with Nick
Complete game in co-op mode
Complete stage 1
Complete stage 2
Complete stage 3
Complete stage 4
Complete stage 5/defeat Skinny Chestknee
Complete stage 6
Complete stage 7
Complete stage 8
Complete stage 9/defeat Darth B.
Complete stage 10/defeat Overlord
Defeat bouncers in stage 3
Defeat robot boss in stage 6
Defeat Big Blue Alien boss in stage 8
Defeat 25 aliens
Defeat 25 enemies
Earn enough energy points in minigame to earn a 1up
Complete mini-game
Destroy one of each type of breakable object
Earn an extra life from high score
Lose 25 lives
Complete the game thrice
Beat a boss with max health
Activate a level password
Activate a cheat code
Collect 25 lives
Collect 25 invincibility powerups
Collect 25 extra attack powerups
Achievement awarded to achievers who achieve all of the achievements
Complete game on Metal difficulty
Complete game on Death Metal difficulty
Complete Death Metal difficulty under 1 hour 15 minutes
Complete Death Metal difficulty under 1 hour 30 minutes
Complete Stage 4-2/defeat Metal Jesus Rocks
Complete Stage 8-2/defeat Alpha Omega Sin
Complete Stage 11
Complete Stage 11-2/defeat Gibletor again
Complete Stage 12
Complete Stage 13
Complete Stage 13-2/defeat Metal Head boss
Complete Stage 14
Complete Stage 14-2/defeat Harvester
Make Metal Head Boss spawn 5 sets of enemies/play complete song within a single fight
Use a Guitar weapon
Use a Grey Alien Arm weapon
Kill 25 Mayo enemies
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