The Porting Kit is an application which ports certain Windows games to the Mac. Similar to "Crossover Mac," the application installs a Windows game using a script and creates a "Wineskin wrapper" and installs the specific Windows game into that wrapper. When the process is finished, you are able to run the game on your Mac. The cool thing about Porting Kit is that it also contains a lot of Free Windows games which it will automatically download and install. It's made so easy that not much knowledge is required to use the application.
For the commercial games, only the setup file of the game is required, which Porting Kit will locate in the download folder and will also automatically install in Porting Kit as an app.