Defeat 20 enemies by shooting from the hip (without aiming with the L button).

Finish the game in Normal Mode.

Defeat 250 enemies with headshots.

Defeat 50 enemies with stealth attacks.

Kill only a single enemy with a BFG9000 blast.

Kill 5 enemies in 5 seconds with the Plasma Rifle.

Defeat 30 enemies with the Wes - 44.

Defeat 100 enemies with headshots.

Get 20 kills using the berserk powerup in a single level.

Gib three or more enemies with a single rocket explosion.

Defeat 50 enemies with the Dragon Sniper.

Find a secret level.