- Moraffs dungeons of the unforgiven (surprisingly good game for its day)
- Ports of call (this is now available on steam for like $5 and surprisingly good)
- Mordor 2/Demise: the rise of ku'tan (oddly enough I prefer the pre release beta version released in 1998 to the final product, but its so obscure most people have never heard of it, and also very, very, VERY difficult. I never even reached level 10 of the dungeon in the original beta after a few thousand hours of play)
- dink smallwood
- STUNTS (old 1990 era racing/stunt driving game, not well known today)
- Windows Elvis in Space (its....odd and virtually impossible to find a full version of)
- Eternam (available on steam and GOG for like $2.50 on sale, weird game from 1992 but pretty good and worth the price)
- Castle of the winds (fairly popular in its day but not many people seem to be aware it exists today, but a really good game for its era)
- Blake stone (available on steam and GOG, released like a week before the original doom so nobody really knew about it at the time. uses the old wolfenstein engine with some interesting enhancements, like food slots, and interrogation system for talking to npcs, moving between levels at will, etc..)
- Conquest of the new world (from 1996, not well known and difficult but a surprisingly good procedurally generated exploration and conquest game that lets you claim and name areas of the world like mountains and such
- Meridian 59, (first commercial 3d mmo, has since gone freeware and open sourced, but i'd avoid the steam official community if I were you, real sketchy stuff going on on the admin side of things that goes beyond in game shit)
- Ancients (an old game from the early 90s released by Epic back when it was still called 'Epic Megagames')
- Ancient evil (sort of a diablo cloneish by design but a surprisingly good rpg dungeon crawler released in 1998, with a good lighting system, interesting magic system and lots of puzzles. Only places i've seen it available are through a few old abandonware sites, also has a sequel)