Deep Silver have announced that Metro: Last Light will be included with the 300 Steam Machine prototypes that will be shipping to lucky people soon. Just the other day 4A Games released the game for Linux, and now it makes a lot of sense why they decided to randomly port the game. 4A will be working on tweaking the game for SteamOS and for the Steam Controller.
The fact that a game of this size will be on SteamOS is a really good sign for Valve's plans to invade your living room. Hopefully we'll see even more games get ported over to Linux in the future. Maybe SteamOS will have a better launch library then we first thought.