EntityPlus
A mod for Quake III Arena by Eraser. Published 11 March 2011.
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EntityPlus is a mod that allows level designers to create single player levels for Quake 3 where the gameplay is more like that of Doom or the first two Quake games' single player modes than the bot matches Quake 3 offers. The project was started up by Eraser but already a bunch of other people donated their skills to the project.
More information can be found at the EntityPlus project page over at Github.