ID Software has released the Quake 2 Source Code. Thanks DosFreak

As with previous source code releases, the game data remains under the original copyright and license, and cannot be freely distributed. If you create a true total conversion, you can give (or sell) a complete package away, as long as you abide by the GPL source code license. If your projects use the original Quake 2 media, the media must come from a normal, purchased copy of the game.

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