|Get used to seeing this screen a lot. It ain't easy, but it's fun.|
Dungeons of Dredmor has a ton of variation and is highly replayable, largely due to the various character builds interacting with the dungeon in completely different ways. It's not class-based, you chose your own combinations of 7 of the roughly 30 skill trees. If you can teleport, turn enemies into meat products, build your own armor from items found in the dungeon, and rob from vending machines, you'll get a very different game then if you choose to be a vegan archaeologist with a pet mustache-golem. I'm not making that up.
Best part: Dungeons of Dredmor is dirt cheap. I got mine via one of the Humble Indie Bundles, but you can pick it up on Steam or Desura for $5 and the expansion is just another $3. The wife and I have logged over 170 hours playing it, and have shown no signs of slowing down. Seriously. You can't beat that value for your money.
As mentioned, I'm working on mods for the game, which I'll link to from this blog when they're ready for release.