"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."