These aren't all remakes/clones. For example: ioquake3 started from the GPL release of the Quake 3 engine from iD software. It is not a clone or remake it is ju

These aren't all remakes/clones. For example: ioquake3 started from the GPL release of the Quake 3 engine from iD software. It is not a clone or remake it is just a continuation. And it doesn't replace Quake 3, it is just the game engine.