Complete The Spiral
Acquire all ammo and health upgrades
Acquire all weapons
Complete a level without killing any monsters
Acquire an ammo upgrade
Acquire an health upgrade
Trigger a hidden message in the password menu
Find Elvis
Solve the puzzle
Complete the game on hard difficulty
Complete the game on very hard difficulty
Complete the game on any difficulty
Complete the game on any difficulty under 20 minutes in a single playthrough
Get a perfect kill count in any level
Acquire the Jetpack
