GitHub programmer ports playable Doom to DSLR camera with 3-inch TFT LCD display — Canon EOS 550D with open-source Magic Lantern firmware uses camera's button as controls, even plays sound
A developer posted their Doom port for the Canon EOS 550D on GitHub.
The game uses the Magic Lantern firmware add-on to run on the camera, and uses various camera buttons to play the game directly from the SD card.