John D. Carmack (born August 20, 1970) is an American game programmer, aerospace and virtual reality engineer. He co-founded id Software. Carmack was the lead programmer of the id video games Commander Keen, Wolfenstein 3D, Doom, Quake, Rage and their sequels. Carmack is best known for his innovations in 3D graphics, such as his famous Carmack's Reverse algorithm for shadow volumes, and is also a rocketry enthusiast and the founder and lead engineer of Armadillo Aerospace. In August 2013, Carmack took the position of CTO at Oculus VR.