Last year I wrote about the Torque 3D game engine wanting to come to Linux and they were attempting a crowd-sourced campaign to finance the port. The campaign was a flop, but a developer has been bringing the support anyways to Linux.
The Torque 3D game engine was already open-sourced and has been used to power Tribes 2, Frozen Synapse, and other titles.
Dusan Jocic, a Phoronix reader and developer, has been porting the game engine to Linux. He was the developer of the OpenWolf engine while lately he's been playing around with the Torque 3D engine. "I want with this engine to provide remake of Wolfenstein Enemy Territory and Tremulous and of course they will be released as FOSS and F2P."