Well.
I WAS going to build model dungeons segments for tabletop games.
Thanks for nothing pal!

Dude, you MUST play Might and Magic : World of Xeen...
That is what hooked me on RPGs in the first place.
[url=]http://www.abandonia.com/en/games/482/World+Of+Xeen.html[/url]
BEAUT graphics but I hated using Dosbox with it - it never felt right...

If you like old-school RPGs but you don't want to be stuck in dungeon all the time try any game from Ishar trilogy. Walking at night through the city was very climatic.

I shamelessly DLed 8gigs of DOS games in under 6 hours and found another game to add this list
Ravenloft Strahd's Possession
The graphics are like any other pre-DOOM fps like Wolfenstein only as an RPG with vampires.
Plus one of the character pictures looks like Wanda Sykes-Hall (see attached picture)
I'm not trying to circumvent GOG or anything because if they where to sell Diskworld 1&2 with all the sounds and character voices I would gladly buy it right now and throw away this striped down pirate copy.

I'd actually recommend Lands of Lore II: Guardians of Destiny if you liked Stonekeep. (Everyone beat me to Eye of the Beholder - but if you DO go for the EotB series I'd say the second game is the best, just my opinion, mind!)
Lands of Lore 2 is another 1st-person RPG with a great story, similar interface, a likeable main character 'Luther' and a bit more of an open world to explore than Stonekeep.
My copy of Lands of Lore 2 just won't work on my machine no matter what I do, though - so good luck tracking down a working copy.

One of the best Slash and Slay Action Adventures games that I have ever played in the past is Blade of Darkness By Codemasters. One can play it as single player or up to 8 players via network. One has a choice of 4 characters Naglfar Dwarven Messenger, Tukaram of the Irkanois (barbarian), Sargon of the King's Knights and Zoe Adventuress and Bounty Hunter. If you can find this game buy it. It has fantastic graphics and a humongus world.

Daggerfall

Eye of the beholder 1, 2 and 3
Dungeon Master
Lands of Lore
Maybe GOG can add these to their catalog?

Dungeon Master was the first RPG that i actually liked and finished. Although i had played others like Bards Tale, i never actually liked them at all.
Its similar to Stonekeep in terms of first person view.
Ultima Underworld 2 (i didnt like the first) is also superb.

lands of lore is one of my favorite games back in the day... nothing too complex but nice story and atmosphere

I have lands of lore. Its a ton of fun.

Anvil of Dawn was quite good.. Still have the original disc and manual somewhere around here :)

Thunderscape had its problems, but I've always thought it was underrated and overlooked. I bought it new for a dollar and had (and still have) a lot of fun with it. Great soundtrack, too.
I could have sworn I've run it on XP, though. I still have my disc, so maybe I should look into that later.

I'll also second the recommendations for Might & Magic. If you ever find Might & Magic Trilogy for a sane price, it's a great buy - it includes MM3 (Isles of Terra), 4 and 5 (which produce World of Xeen when installed together), and the fan-made campaign Swords of Xeen (which I think never had a standalone release). I haven't played Swords, but 3, 4 and 5 are among my favorite classic dungeon crawlers.
If you're looking for something a little more modern, Wizardry 8 is a lot of fun. I never got very far in it, but I've been meaning to go back to it one of these days.