Runic Games' Torchlight, although you probably know them best as the guys who worked on Mythos. The MMO version of Torchlight isn't out for another 18 months or so, but you can get a taste of it as of today, which is of course the game's release date -- imagine that!
Not only is the game developed by the former Mythos team, it's also headed by Max Schaefer and Erich Schaefer, co-designers of Diablo and Diablo II. Speaking of those games, we hope you liked their music, because the same man who wrote it worked on Torchlight as well. The pedigree is definitely high, and from our hands-on experience it shines through exceedingly well.
So will you be getting Torchlight? At the low price of $20, it's not a hard sell considering the quality of the game. Plus, with full mod tools being included in that price, free fan-made content should be falling down from the heavens in no time flat.