Have been using most of my time learning more important functions on my new iMac. Today I decided to take a break, relax and play the chess game. I know how to play chess. The game seems not to know how to play correctly. After a few moves and when I have captured a few pieces.............out of nowhere the opposite side will put a piece back on the board .......or even add a second queen to the game. What a disappointment this game is. Anybody know what could be going on with this screwed up chess game?