OS X includes a pretty darned impressive chess game game. The marble skin in Tiger gives the clearest pieces.
I'm no chess player, and my 8 yo is even worse, so we play it in 'fastest' (dumbest mode). Only it seems to behave differently in Tiger and Panther.
On my G3 iBook running Panther it tends to beat us fairly handily -- even in 'fastest' mode and even when we cheat and 'take back' dumb moves. On my far more powerful G5 iMac, however, I can beat it fairly easily in that mode.
So what's the story?
Does it learn? (God, I hope not.) Is there a bug in the 10.3.9 version so it behaves as though it were in mid-range smarts? Did Apple dumb it down for Tiger (thank you)? I'm curious.
Update 9/14/05: I'm convinced there are a few bugs. I think in 10.3.9 the prefs don't always work -- sometimes Chess.app works at its default setting despite what the gui shows. In 10.4.2 Chess.app at its lowest setting is very beatable (it looks one move ahead, so it will quickly trade a pawn for a queen). On the other hand in 10.4.2 we saved a game with a bishop that couldn't be moved. He was stuck!