Here is the full list of all 12 Alan Wake's American Nightmare achievements worth 200 gamerscore.
You made it through the night and enjoyed a nice sunrise in one of the Arcade levels.
You used Mr. Scratch’s own trap to destroy him.
You secured the coolant tanks at the observatory.
You rewrote reality and brought down the satellite.
You took out two Splitter spawns with a single shot.
You reached the relative safety of the motel.
Get a six-minute survivor streak and over 100,000 points in an Arcade level.
Unlock all of the Nightmare Arcade Mode levels.
Survive an Arcade level using nothing but the flashlight and handheld flares.
Get 70,000 points in any Nightmare Arcade level.
Find all of the manuscript pages.
Defeat 2,000 Taken.