Torchlight 2. However, the game is now available for pre-purchase on Steam, which should serve as something of a reminder. The game doesn't yet have a firm release date other than this summer, but you can still drop your $20 and have the game ready to play on launch day.
The original Torchlight was hailed by many as the spiritual sequel to Diablo II (and some assumed it would also be the closest we'd ever get to an actual sequel). Torchlight 2 boasts more character customization, more pet customization, improved fishing and pet management, a new set of classes, and of course all of the same hack-and-slash gameplay that the first game featured. If you're a fan of the genre, that third installment likely has your eye for the moment, but you might want to see how the other half lives as well.