Deathless

Deathless is a four-episode mod for Doom, famous for being made in nine days. It was developed by James Paddock and released on November 9th, 2008. Each level was made with a specific color scheme and with the overall arching theme being short-spurt levels that can each be completed within minutes. Although not developed, licensed, or published by id Software, it is officially supported by them. It was later released as a free add-on for the 2016 remaster of The Ultimate Doom.