Card Crawl is a perfect combination of RPG and solitaire which you can play in spurts of less than five minutes. In this game, you control a character (represented by a card with a life bar and gold) who is trying to loot a dungeon full of treasures and monsters (which are also represented by cards).
The gameplay is much simpler than it first seems: your character can hold a weapon card or shield in each hand, and you can put a potion card in your backpack. Each turn, four cards are put on the table, and you can't take anything else until you use or remove three of them. Your goal is to clean the deck.
There are four different game modes and lots of cards, such as various potions, special skills, monsters, weapons, shields, etc. You can see all the cards before playing and read about their special rules.
Card Crawl is a very original game which combines two disparate genres (solitaire and RPG) for a great gaming experience. The look of the game, which is a little Burton-esque, is an added plus.