The Game Developers Conference (GDC 2014) is getting set for next week in San Francisco and Crytek has an early announcement. Attendees of the event, at presentations and demos in their booth, will see CRYENGINE running natively on Linux. The engine has also been updated to include their enhancements first seen in Ryse, such as "Physically Based Shading".
This announcement gives promise to SteamOS as a viable gaming platform because games which license this engine would have an easier time porting over. That said, Unreal Engine has offered Linux compatibility for licensees, to very limited uptake. Sure, Steam could change that trend because a chicken or an egg could happen at some point — it does not matter which comes first. Still, this is not the first popular engine to be available for Linux.
Their "Physically Based Shading" system is quite interesting, however. As I understand it, the idea is that developers can make (or maybe use) a library of materials and apply it across any game. This should hopefully reduce the number of artist man-hours to produce a generalized optimal shader. It is much slower to tweak specular highlights and vector math than it is to say "you… are gold… be gold".
The official GDC expo will take place March 19th – 21st but I expect news will flood out from now until then.