Metro: Last Light is powered by the 4A Engine, having been developed by the 4A Game Studio. The game was originally released earlier in 2013 for Windows and game consoles but has now been brought to Linux via Steam. Firing up the Steam Linux client today will reveal this new Linux game title.
For those wishing to learn more about Metro: Last Light, visit its web-site and checkout the game trailer below. Thanks to Christopher May for pointing out this new AAA worthy Linux title.
Update: At this time the SteamDB listing for Metro Last Light on Linux is in place but it doesn't appear the Linux game binaries are yet uploaded.