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