-Estimated achievement difficulty: 7/10
-Offline: 12/12 (200)
-Online: 0 (0)
-Approximate amount of time to 200: 10-13 Hours
-Minimum number of playthroughs needed: 1
-Number of missable achievements: None (Chapter Select)
-Do cheat codes disable achievements? No Cheats
-Does difficulty affect achievements? Yes (Survivor which is in Arcade Mode)
-Glitchy achievements: None reported yet
-Unobtainable achievements: None
Alan Wake American Nightmare has 2 different modes: Story and Arcade. The achievements are essentially split between both. There is only one achievement based on difficulty and that is Survivor in Arcade Mode. There are a good amount of collectibles which are the manuscripts. They are the only collectibles you need for an achievement. Luckily, you can replay scenes to grab the ones you missed.
Step 1: Story Mode
First off, play Story Mode and collect the manuscripts. This will also prepare you for Arcade mode. You'll know the best ways to kill enemies and have unlocked supply chests from the collectibles. Also, you will be familiar with all enemies. The story consists of 3 acts which each visit the same 3 areas. This is 9 chapters total and it doesn't take all that long to complete the chapters. While playing, the only achievement you must worry about is for finding all manuscripts. Everything else is story related. You will have a total of 100 once you are finished.
Step 2: Arcade Mode
Now that you're done with story, it's time to tackle the wave based mode. You'll have to unlock all of the Nightmare versions of each level by unlocking the stars. To gain higher ratings you must score extremely well. After you have unlocked all of the Nightmare modes, play the level you feel most comfortable on and try to gain "Survivor". You will also need to play one level without using any type of guns or weapons (flare guns you cannot use either). The Arcade Mode achievements will likely be the harder of the batch. You must earn 24 stars in arcade mode to unlock all Nightmare levels. You must dodge and fight your way through. Try to kill enemies as fast as you can to get the most amount of points. The difference with Nightmare mode is that the enemies take more hits and there are no breaks or "waves" happening. They just come in constantly.
Step 3: Mop Up
If you haven't obtained every collectible once you finished the game, you may replay scenes to finish them off. Also, you will be replaying arcade mode a bunch. If for some reason you are extremely good at the game and did everything quickly, you may just be missing the "kill 2000 taken" achievement. In which case, you can now grind out to finish the game.
This game will take a good amount of time to complete, and the arcade mode will be frustrating. Some will wonder why online cooperative arcade play isn't an option (Barry would be nice). Overall this will be a satisfying completion. The quality matches the actual game "Alan Wake".
[x360a would like to thank Tyger7 for this roadmap]