one decently-sized non-linear map, boom-compatible, by Thelokk. You can get it here.
Self-described as "Penelope.wad is a sort of bookend to my first year of mapping, and a distilled extract of everything I like in my mapping soup: complex architecture, out-there texturing, strange progression and a whole lot of atmosphere." in the Doomworld thread here.
I find myself in agreement, as someone who playtested a few of her other maps, it particularly reminds me of pieces from Untitled. Moody, gloomy, suppressed, and sometimes slaughter-ish. Perhaps try it if you have a half hour and don't mind light platforming, rocketing imps, and wondering what kind of world this place used to be.
a simple photo:
