Castle of the Winds is a great dungeon crawl RPG written by Rick Saada and published in 1993 by Epic MegaGames. Episode 1, A Question of Vengeance, was released as shareware, while you had to pay for Episode 2, Lifthransir's Bane (which has recently released into the public domain). It features simple, tile-based graphics, tons of monsters, lots of cool weapons, armor, and items, and a bunch of nifty magic spells. It also had a system of enchanted items reminiscent (preemptively) of Blizzard's Diablo. It has the look of a game written in Visual Basic, but I don't know for sure.
Castle of the Winds is set in a world inspired by medieval Norse mythology. It's also highly derived from Nethack and D&D, and I suppose could be considered a Roguelike game. It has nowhere near the kind of insane interactivity that Nethack does: the DevTeam thought they should keep it simple. Unlike Nethack, however, there's a town at the top that you can go and buy stuff from.
Just a few of the nasties you'll run into: Kobolds, Skeletons, Orcs, Gelatinous Globs, Animated Statues (of various materials), Manticores, Wights and Wraiths, Bear Men, Dragons (of various colors and ages), Elementals, and Giants
I wasted a LOT of time playing this game. It gets very difficult at the bottoms of the dungeons. | 
