Poly Puzzle is my first 'original' program to make use of Tk's canvas widget. It was inspired by a plastic puzzle named Beat The Computer which came in an array of sizes and loud colours.
It now has trays with polygons based on hexagons, squares and equilateral triangles. The new round tray is based on smooth triangles, and isn't quite as cute as the original puzzle #0.
..I had planned to incorporate a computer solution feature. This would be handy for the actual plastic game - which you have to put away at the end of the day - but on the computer there are no little pieces to lose under the carpet ;>. More to the point - it would require quite a bit of programming / math!