I had played the free version of this game a while ago, and I didn't really like it then. It seemed a bit too sparse and simple.
Boy, was I wrong. This is actually a pretty complex little game. And it is hard. Brutally difficult. Super Meat Boy difficult.
It is a rogue-like, and has nods to history like the crazy shopkeeper who will go nuts and kill you even anything sketchy happens near him.
The hundreds, thousands of ways that you can screw up and insta-die are infuriating, yet fun. The randomness and scarcity of items adds to the experience, and nothing is more exciting than opening a chest and getting a compass, or spring boots, or a cape.
This game looks great, plays great, and I spent 7 hours today spelunking my cares away.