https://github.com/ec-/Quake3e

You would need to either pirate q3a assets or use OpenArena’s restored content mod.

www.openarena.ws

You are likely to get turbodunked initially as the remaining playerbase are REALLY good and the movement mechanics are un-intuitive.

Outside EU and NA peaks finding a full server can be a bit rough.

There are several practice bot mods, my favorite is called “brainworks”.

It has been forked several times, but that works.

There are dozens of us!

Quake 3 sourceports, my favorite is quake 3e