What is ioquake3?

ioquake3 is a free software first person shooter engine based on the Quake 3: Arena and Quake 3: Team Arena source code. The source code is licensed under the GPL version 2, and was first released under that license by id software on August 20th, 2005. Since then, we have been cleaning up, fixing bugs, and adding features. Our permanent goal is to create the open source Quake 3 distribution upon which people base their games, ports to new platforms, and other projects. We have developed the perfect version of the engine for playing Quake 3: Arena, Team Arena, and all popular mods on modern platforms like Windows 7, 8, and 10, Mac OS X Mavericks and  Mac OS X Yosemite.

About the name:

The project came out of the icculus.org software incubator, which is why it is called ioq3, or call it ioquake3 if you’re not into the whole brevity thing. icculus.org has lots of awesome software, you should check it out. Please don’t capitalize the Q, in ioquake3, it just looks bad.

What can I do with ioquake3?

You can use it to play Quake 3: Arena, Quake 3: Team Arena, and the mods people have made for those games.
You could Make your own game from our source code on gibhub.
Or play a game that someone else has made.