Possibly the best arena shooter ever existed, which sadly killed the Quake franchise on the long run.

Quake III is fast paced, hectic and most importantly fun, with an engine that pretty much defined an era in video games.

If you never played Quake III before, or you just became a Quake fan thanks to the Quake II remaster, give it a try. It has a decent, gladiator style single player mode, which is pretty much the multiplayer deathmatch mode with bots.