Kill three or more enemies by shooting a grenade

Complete Act 2

Kill 15 enemies with a stealth kill

Kill 15 enemies while playing as the Darkling

Escape the asylum with help from the inside

Complete Campaign Mode On 'Braindead'

Complete Mission 10 (Any Difficulty Level)

Kill all enemies in the beach houses without causing an alarm ("Leave No Man Behind")

Take 50 headshots in single player

Kill 20 enemies from a distance of 600m or greater

Complete any single player mission without using med kits, but taking damage

Complete Mission 9 (Any Difficulty Level)

Complete Mission 7 (Any Difficulty Level)