"OpenArena
This is probably the most popular game based on the ioQuake 3 engine. It's practically a Quake 3 clone, with its own free data, so if you are used to Quake 3, you will learn how to play this one very easy.
"You can use your old cfg file for settings and scripts, and the menus resemble the Quake 3 interface in detail.
"All the modes available in Quake 3 are also available in OpenArena: we have DM, TDM, CTF and Tournament. To these, the game also adds four more modes of its own: Elimination, CTF Elimination, Last Man Standing and Double Domination. It includes both new maps and player models, together with new (and more appealing in my opinion) textures, but some of the CTF maps looked to me a little poor in detail. Of course, the bunny hopping feature is available in OpenArena too."
