AMD Radeon, NVIDIA GeForce Linux Comparison For July 2013
Here's one of our first broad looks at the Unvanquished open-source game, which is powered by the Daemon engine and this test profile is using its new GL3 renderer. Most of the graphics cards were able to run game just fine with near-60 FPS frame-rates but the GeForce GT 240 / GTX 460 / GTX 550 Ti results were a bit odd.
Aside from Unvanquished, Xonotic is another one of the more promising open-source games that also is capable of delivering good graphics / art assets.