Here's some achievements I thought of for Killing Floor
Kiss the Stalker: Melee kill x number of stalkers
Executioner: Decapitate x number of specimens with melee weapons
Shut your mouth: Headshot x number of sirens
These are all the achievements I can think of for now. If there are any more, I'll edit
Kiss the Stalker: Melee kill x number of stalkers
Executioner: Decapitate x number of specimens with melee weapons
Shut your mouth: Headshot x number of sirens
These are all the achievements I can think of for now. If there are any more, I'll edit