DLC: Severed

Grind House (20G)
Severed: In the grinder room, cause an enemy to die in the grinders.

King of the Hill (20G)
Severed: Defend the quarry platform until the door unlocks.

Peng Me Again (20G)
Severed: Find the Peng treasure in Severed.

Remember the Alamo (20G)
Severed: Kill 16 or more enemies in the final last stand combat sequence.

The Veteran (50G)
Severed: Complete on Zealot difficulty.

Secret Achievements

The Betrayal (50G)
Severed: Complete Chapter 1.

The Sacrifice (50G)
Severed: Complete Chapter 2.

Ship Shape (20G)
Severed: Take out the gunship within 30 seconds.