There is even a source port

I'd have said Lands of Lore: The Throne of Chaos, seeing that Eye of the Beholder 2: The Legend of Darkmoon is not available on GOG - I think those two are my favorites of all the classic tile-based dungeon crawlers. But then again, if you want to use graph paper, Lands of Lore might not be the best choice, since it has an automap ... So I'd recommend Legend of Grimrock with the hardcore automap off mode, if you're looking for a classic tile-based dungeon crawler.

Arx Fatalis, Ultima Underworld and the Might & Magic series are good suggestions, too, but if I'm not mistaken they all have automaps and drawing the maps for them yourself wouldn't be that easy, as the first two are not tile-based and the latter have larger outdoor areas which I personally wouldn't think much fun to draw (too much space, too few walls).

You could also start with the free Dungeon Master clone <i>Return to Chaos</i>. It doesn't get much more classic than that and it will cost you nothing. ;)

I vote AGAINST Legend of Grimrock, which is nice as an hommage but average as a Dungeon Crawler.

I vote for either Ultima Underworld (real 3D) or Lands of Lore (pinacle of the "traditionnal" Dungeon Crawler).

WHAT .. but but but why...would you mention this source port... why why??
i'm already playing way to many old games as it is. My backlog is getting bigger and bigger and now this...
*sobs in a corner

Assuming you really want to make your own maps (I thought I was the only one left alive who enjoys it):

For real time and tile based, start with Dungeon Master. If you like it, then try the ultimate mapping challenge: Chaos Strikes Back.

If you want turn based, start with Might&Magic 1 or Wizardy 6.

if you liked it on ds you should give orcs and elves a try.

Also why hasn't anybody mentioned Lands of Lore? Is it considered too hard for a first timer or do you guys don't like it?

Wow... I trued them both (I chose free version of Desktop Dungeons), and they are both awesome. Highly addictive and relaxing.

Sorry, in that case I guess I shouldn't mention just how many source ports and engine replacements I've accumulated then >_<

Ultima Underworld 1&2
Lands of Lore 1
Daggerfall
LoG

The Legend of Blacksilver, pirate a copy now!
These are good too.

Gauntlet fucking Legends

http://www.youtube.com/watch?v=tU6SlgGQjCE

Underrated game is underrated I will kill for another game that plays exactly like this or re-released with updated graphics like Super Street Fighter 2 Turbo HD Remix and Perfect Dark Xbox Arcade honsetly this game was IMO better then Diablo

I hate to draw fire but that game was only fun for me while drunk with buddies... of course a lot of games are a lot more fun drunk... fuck I'm drunk right now, why am I talking to you? GAMES!

Another vote for Arx Fatalis. Draws heavily upon UU, very atmospheric, cool sounds, neat magic system, kind of pretty.

Diablo (the first one): it's modern, it's a dungeon crawler, has a way better atmosphere compared to Diablo *OMG AUCTION HOUSE WE'RE RICH!!!* III.

*EDIT: Oh nevermind, I read that you want to draw maps and Diablo randomly generates the game world. Then the Eye of the Beholder saga should be a better fit for you...