FrozenSand

Urban Terror is a freeware multiplayer first-person shooter video game developed by FrozenSand. Originally a total conversion of id Software's Quake III Arena, FrozenSand released Urban Terror as a free standalone game in 2007 utilizing ioquake3 as a game engine. While the game engine is licensed under the open source GPL, Urban Terror's game code is closed source and its assets are freeware but not open content.