Base Ganymede is an episodic doom 1 project set on one of Jupiter's moons named Ganymede which is sticking to vanilla DooM map limits. Planning on 3 episodes, the first was completed late 2009 and can be found in the downloads section. The final ep was completed in Jan of 2012 & released with all 3 episodes back to back after 2 and half years of work.
Another 8 vanilla compatible levels set on the moon Ganymede. For your average skill level Doomer (you all hit UV anyway), but speedrunners have certainly been catered for as well!