Scattered Ashes is a 10-level wad made in 3 weeks as a part of the NaNoWADMo 2018 project.
Each map takes about 5 minutes to play through. The gameplay is pretty standard in some maps, but in others it can get quite gimmicky, so there's a bit of variety in terms of that. The wad is split into 2 episodes. One centers around the colors gray and black, the other around green.
It was tested with GZDoom and Zandronum (and it should be co-op compatible). Difficulty options are implemented.