I ported the card game Set (http://en.wikipedia.org/wiki/Set%20(game)) to the 83/84 calculators using axe. I used Runner112's GreyLib library to achieve near perfect greyscale.
You can download it here (http://www.ticalc.org/archives/files/fileinfo/470/47062.html).
Like the original game, each card has four properties (number, color, shape, pattern). A "set" is a group of three cards in which every one of the properties is either the same or different. (but not two cards alike with only the third different).
Twelve cards (or more if needed) are laid out and you have to try finding a set. When you find one, you press [Graph] to call it, and then select the three cards. You get a point and those cards are replaced. Calling "set" incorrectly causes you to lose a point. (Though you can disable this penalty in the settings.)
If you wait to long then the calculator will "find" a set first and get a point. This time is defaulted to about 20 seconds (on the 15mHz calcs at least), but you can adjust it in the settings for an easier/harder game.
Arrow keys - move cursor around
Graph - Call a set
Graph/2nd/Enter - Select cards (after calling a set)
2nd/Enter - Deal new cards (after the calculator calls a set)
Trace - Enter/Exit the settings menu
Clear - Exit
It looks really cool, especially the grayscale!