1. It supports three levels.
2. It supports undo.
3. There is a rank system. Every time you win the computer you will get 100 points. If you get a draw game, then, you get 50 points. Even if you lose it, you can also get 1 point.
See game rules: http://en.wikipedia.org/wiki/Chess
Download and try it to see your name in Top 100.