-: ATTN - if your game won't start, READ HERE :-

Go to Applications > Utilities > Activity Monitor. You'll see the game in a long list of processes, probably highlighted in red. Select it then click on the little X in the top left corner of the window, below the green, red and yellow Xs.

You're welcome. I've been waiting for weeks for a MacBook Air user to finally try the fix and post their results, it's the only way we can work out fixes :)