Here is the full list of all 12 Alan Wake's American Nightmare achievements. It takes around 8-10 hours to unlock all of the achievements on Windows.
You secured the coolant tanks at the observatory.
You used Mr. Scratch’s own trap to destroy him.
You made it through the night and enjoyed a nice sunrise in one of the Arcade levels.
You have unlocked all of the Nightmare Arcade Mode levels.
You got 70,000 points in a Nightmare Arcade level.
You took out two Splitter spawns with a single shot.
You got every manuscript page in the game.
You have defeated 2,000 Taken.
You got a six-minute survivor streak and over 100,000 points in an Arcade level.
You survived an Arcade level using nothing but the flashlight and handheld flares.
You rewrote reality and brought down the satellite.
You reached the relative safety of the motel.