Complete "Second Helpings"

Kill 500 enemy soldiers while not in a Vehicle

Kill 6 enemies at once with Line Gun's Alt-Fire (single player only)

Survive the Train Sequence

Upgrade 1 Weapon completely

Collect 10 Semiconductors

Dismember 25 Necromorph Limbs (single player only)

Perform 20 headshot kills in one round

Complete the tutorial

Lose your head three times in a single match

Complete a Bonus Objective.

Kill 20 enemies with the longsword

Defeat your first enemy.