Nex-u-is? Or Nes-uiz? Or more simply Quake III Team Arena?
That last one might be the best way to remember it because Nexuiz is a fantastic-looking Quake III Team Arena clone with some neat "mutators" that can really randomize the action and keep games interesting by forcing a change-up of strategy when the floors are suddenly super slick or everyone starts bouncing around like rubber balls.
