With the folder rename and put .app at the end. hoodie messed up the .app process.
Okay forget winrar then and try unarchiver. That should beable to extract rar files as well.
Here is an tut. video
How to Open Rar Files on Mac - YouTube
Make sure to redownload the mac version of the game just incase. extract the rar file and it should extract and .app file, double click it and it should start. I think, since macs make it way to confusing.