OpenArena is a community-produced deathmatch FPS based on GPL idTech3 technology. There are many game types supported including Free For All, Capture The Flag, Domination, Overload, Harvester, and more. There are 17 unique player models to choose from and 12 weapons.
Does what it's meant to do more or less. Really, you can't complain, I've never played Quake 3 except for on the Dreamcast back in the day, but compared to Quake Live and other current arena shooters this one is severely offensively biased. It gives it a unique feel. Yeah the graphics are some of the worst we've ever seen and there are a lot of things that feel unfinished, but this charming little frag extravaganza will appeal to fans of hardcore arena shooters just fine, and it'll run on nearly any computer you have lying around in the darkest corners of your attic that nobody's been to since you upgraded your computer in 2001.
Bottom line, not for everybody, but if you're a hardcore FPS fan the learning curve isn't very steep and you can have many thrilling moments playing a great shooter. I've wasted hours in front of the screen playing Open Arena, it isn't Quake Live, but it's fun, and, like I said earlier, charming.