I've designed a set of puzzles called Subway Shuffle, and written a Mac program to play them, here:
http://www.subwayshuffle.com
(Requires 10.3 or later.)
The flavor is rather like the puzzle Rush Hour. This one is set in a subway system. Many of the puzzles look quite simple, but are very complicated. Most are the result of a computer search for the hardest puzzles subject to various constraints.
Enjoy! And please give me any feedback or suggestions. And feel free to pass the link along to friends etc.
Thanks,
Bob Hearn