This isn’t a game, per se, but it’s rather fun to play around with and I think will eventually evolve into some sort of game.
Basically, it randomly generates a maze using the Drunkard’s Walk algorithm, then solves it with either A* or backtracking. You can also do a few other fun things with it.
More info here:
http://www.otcsw.com/maze.php
Webstart here:
http://www.otcsw.com/webstart/AhMaze/AhMaze.jnlp
Oh yeah, and it’s open source (there is a download link on the web page), so if you’re interested in learning any of these algorithms go ahead and give it a look.