Metro: Last Light is now available for play on Linux! As a Steam Play title, any Steam version in your library will work on Linux, PC, and even Mac.
Metro: Last Light will also work natively on Steam Machines running SteamOS once it's available!
Nvidia owners should experience no problems with the game. 4A Games and AMD are working together on improving performance on Linux and are waiting for updated drivers from the graphics card manufacturer.
If you have an AMD card and are running the latest version of Ubuntu (13.10 x86) you will need the latest beta driver from AMD to start the game, which you can download from here: http://www2.ati.com/drivers/beta/amd-catalyst-13.11-beta6-linux-x86.x86_64.zip
We'll keep the community updated on developments on the AMD side as soon as we receive them.