The game launched last month on November 10 on Xbox One, with the PS4 and PC version said to be coming at a later date. The PlayStation 4 version of Rise of the Tomb Raider won’t be out until late 2016 however due to Microsoft’s platform exclusivity deal they signed with Square Enix to see the game release on Xbox One first.
When Rise of the Tomb Raider was announced back at Gamescom 2014, Square Enix stated an early 2016 release window for the PC version, although no official announcement has been made since. Judging by the fact though that the game now has a Steam page, as well as stating that Rise of the Tomb Raider will be available “January 2016”, I think it is safe to assume that the game will be available on PC by the end of January. In addition to Steam, Amazon France also claims the game will get a January release, citing the 29th at the release date.