"All Doom Levels are Straight Line now" says the description for Linear Doom. "No more mazes." This self-described "jokewad" by modder DeXiaZ released on April 1 takes all of Doom's classic levels and tightens them down into one long corridor. There's enough room to strafe a little so you can still potentially dodge those imp fireballs, but otherwise this is just a straight line run through all of Doom's enemies, weapons, and pickups one after the other. I look forward to seeing the speedruns of this.
You can download Linear Doom from ModDb.