Serious Sam 3 was one of the original games on Steam for Linux and is available to everyone since Valve's Steam Linux client went public. Serious Sam 3: BFE is developed by Croteam and the latest in the Serious Sam franchise. The game is powered by Serious Engine 3.5 and was first released for Windows in 2011.
Published yesterday on Steam was Serious Sam 3 Update 176695. This latest "public beta" of Serious Sam 3 addresses several improvements and fixes to the game itself. There's also several Linux-specific fixes to the game, per the update announcement.
This new Serious Sam 3 update on Linux improves text input, supports the clipboard for copy/paste, fixes wrong characters for certain keys, generates a stack dump upon crashes, attempts to restore the desktop resolution when encountering a fatal error, and supports launching the dedicated server from the Steam client.