Kill 1000 enemies.
Complete "Lunar Apocalypse" on any difficulty.
Step in a pile of excrement.
Complete "L.A. Meltdown" on any difficulty.
Finish a secret level.
Kill every enemy on a level.
Tip an exotic dancer.
Find a secret area.
Listen to Developer Commentary (Use at least one trigger).
Find Sam in "Mirage Barrage".
Find Luke in the Level "Lunar Reactor"
Find the Doomguy in the Level "Death Row"
Kill a Firefly Trooper while it's flying small.
Use the hookah in High Times.
Complete "Alien World Order" on any difficulty.
Complete "The Birth" on any difficulty.
Kill 5 bad guys with one shot.
Complete "Shrapnel City" on any difficulty.
Kill 10 bad guys in 10 seconds while on steroids.
Find 70 secret areas.
Step on 40 enemies after using the Shrinker on them.
Burn 50 bad guys to death.
Carry all weapons with ammo at once.
Use the Incinerator
Finish the "Hollywood Holocaust" level in under 3 minutes.
Finish any level on "Damn, I'm Good" difficulty.
Use a cheat code.