I can't open the game.
What exactly happens when you try to open it? Maybe this can help you: http://www.cs2d.com/faq.php?show=err_launch#err_launch
That's weird. I already got a report from someone else with the same problem but I don't understand it because the file is in the archive for the mac download. To fix it you can try to download the windows zip archive and extract it into your CS2D folder on your mac. This should add all required files.