From the idTech 4 source code as GPLed in 2011, to "any system that supports OpenGL 1.4 with ARB shaders, SDL and OpenAL". DOOM³ had third-party proprietary Lin

From the idTech 4 source code as GPLed in 2011, to "any system that supports OpenGL 1.4 with ARB shaders, SDL and OpenAL". DOOM³ had third-party proprietary Linux/Mac releases back in The Day, but now it's open source and available on many other OSes too.