The Ultimate Doom

The Ultimate Doom (or The Ultimate DOOM as a brand, and informally "Ultimate Doom") is an expanded version of Doom released on April 30, 1995, that adds a fourth nine-level episode to the game, Thy Flesh Consumed. The enhanced version was made as an incentive in the distribution of the boxed game through retail stores and venues, although to be fair to fans who had previously registered Doom, id Software provided them with a freely available patch to upgrade their copy of Doom version 1.9 to The Ultimate Doom.[1]