Doomsday 2.0 portable game engine just released, is an open source, portable game engine for classic first person shooters. Doomsday supports many games including the classic first-person shooters DOOM, Heretic and Hexen. Lets you enjoy the original games using modern technology, including high-resolution OpenGL graphics, 3D models, and dynamic lighting effects. The Doomsday Engine is available for Windows, Mac OS X, Ubuntu and most other Unix platforms. Doomsday 2.0 changelog from developer: The major milestone we are achieving with 2.