Kill a Witch-Bride of Achriman.

Blow a Major Biomechanoid into pieces.

Kill an enemy using the Mutilator.

Defeat the spaceship.

Kill the kicked enemy while it is still in the air.

Squash 10 Hatchling spiders.

Kill an enemy with a gib torn from another enemy.

Finish the Legend of the Beast campaign in single player or cooperative.

Finish Serious Sam: The Second Encounter

Destroy an enemy cannon with your own cannon.

Kill 100 enemies with Serious Damage active.

Kill at least 30 enemies with a single Serious Bomb.

Find at least 30 secrets in single player.