I just finished Breach (Doom Retro, Smooth and Black OPs mods) last night, and despite it being shorter than I expected, I thought it was amazing with what the author had to squeeze out of the Vanilla Doom engine. Does a WAD need to have 32 or even 12 maps to be enjoyable? Of course not! I know there's Suspended in Dusk, Swim With The Whales, and the DBP mapsets, but what, in your humble opinion, excels in atmosphere, map design, and gameplay regardless of the numper of levels?