PlanetQuake pointed out Fitzquake SDL, a Simple DirectMedia Layer port of the Windows-only Quake client Fitzquake. The project is still in beta, so be sure to give the README a look. Here’s the aim of Fitzquake itself:
My primary focus is fixing a lot of the rendering bugs which made glquake inferior to the software renderer. My secondary focus is adding conveniences for mappers and general users. I am also slowly adding support for new modding or mapping features such as skyboxes, fog, and colored light.
Download: [ kristianduske.com ]