J.A.C.K.

J.A.C.K. is a cross-platform level editor designed for games with a Quake-style BSP architecture, such as Half-Life, Quake, Quake II, and Quake III. It aims to incorporate the best features of existing editors and support Source Engine and Unity in the future. J.A.C.K. currently supports level design for Half-Life , Quake , Quake II , and Quake III .