The game lacks a back-up system, meaning that each episode must be finished from the beginning. The floors and ceilings are also not texture mapped. SNES Doom features 22 levels from the PC version, but the player's heads-up display does not take up the whole screen. The game does not use the Doom engine, but features a custom engine, known as the Reality engine, programmed by Randy Linden. The cartridge features a Super FX 2 chip, and Doom was one of few SNES games to feature a colored cartridge the NTSC release was available in a red casing. The Super Nintendo version of Doom was published by Williams Entertainment on September 1, 1995, near the end of the system's life cycle. A screenshot from the SNES version of Doom
