A friend of mine recently wrote a very addictive game called Pattrns. It is based on the card games Blink and Set. The object of the game is to make a set of matching patterns, either in order and color or color and type. It is surprisingly difficult in the begining, but with the newest version help screens have been added that make the learning curve much shorter. The latest version online also has some very clever sound effects and the ability to change the levels. If you are familiar with Blink or Set then you will probably be able to jump right in and play, but if you are new to the game I would suggest you begin your Pattrn matching career on the "Just Learning" or "Have Some Fun Level".