Found the Adminstrator's office.

Released the emergency lockdown.

Survived first encounter with the beast.

Blew up a door with a barrel.

Burnt a corpse to a nice char.

Lit up a fuel puddle.

Used meat to lure rats away from a corpse.

Acquired the lighter.

Used gas on the beast.

Heard the message on the radio.

Discovered the beast's nest in the chapel.

Retrieved the Foreman's dogtag.

Found the Dynamite.

Found the Cutters.

Found the detonator handle.

Blocked the beast's path out of a hole.

Escaped the bunker.

Finished the game.

Acquired the shotgun.

Acquired the gas mask.

Acquired the rabbit doll.

Blew open a door with a shotgun.

Found all the maps.

Sent the beast back into the screaming darkness.

Hurt the beast by triggering a trap.

Showed the beast the bunny.

Disarmed a trap.

Blew up lots of rats with a single grenade.

Shot at the visions in the tunnels.

Got the cutters and locked the cell again without the German Prisoner dying.

Opened all the lockers.

Found all pocket bags.

Quit the game right as things got interesting.

Blasted a rat with a shotgun.

Re-acquired the rabbit doll.

Opened every vent and cut every chain.

Retrieved every note.

Never dropped nor stored an item.

Completed the game without saving.

Completed the game on a custom difficulty level.

Completed the game faster than all developers at Frictional.

Burnt a lot of dead bodies.

Completed the game on Shell Shock difficulty.

Collected all the other achievements.