It's been delisted on Steam except for the DLC.
Topic on Talk:Alan Wake
The music rights expired, and sadly it's likely too costly to renegotiate them. Only people who purchased it from Steam or other online outlets before it went off sale can still download it. The only legitimate way now is probably to buy an existing physical copy from someone. Edit: There's a TV series being made though!--Drat (talk) 15:15, 23 August 2018 (UCT)