Wine is free, but you still need to have a copy of the game. The wrappers require an installation program like Wine(Skin), Cider, CiderX and so on. You can install custom 'wrappers' which allow you to run or install Windows software on your Mac. This program also requires you to have a copy of Windows (money!). You buy Parallels Desktop (costs money!) which doesn't require you to reboot your Mac every time you want to use Windows. The problem here is: Should I buy a Mac just to install Windows on it? (I believe you have to own a copy of Windows, too which costs additional money as well.) You use Boot Camp on your Mac to run Windows. I know there are several ways to play Windows games on a Mac. I've always been into gaming, but playing Starcraft 2 over and over gets really boring once you think about all the possibilities you would have if Mac ran Windows games natively.
No big games (with the exception of Portal 2 and Starcraft 2) have been released for Mac this far. I've always been a Mac fan and the way game developers treat Mac users is just sad.