For those having a problem with the Mac version:
First, it has NOTHING to do with the .rar compression. It has to do with some incorrect permissions on a couple of files in the application.
Jad1239 has the fix. I'm retyping it here, because there was a minor typo in his fix.
1.
Open the Terminal app, then enter the following in the terminal (don't enter the quotation marks):
2. "
cd <game directory>". For example, if you put the game in /Applications/RenPy, "cd /Applications/RenPy"
3. "
cd Vis.app/Contents/MacOS". This takes you to a directory inside the game application.
4. "
chmod +x Vis". There's a file here called "Vis" that doesn't have permission to execute. This makes the file executable.
4.a. "
ls -al Vis" will show you the permissions on the file if you are interested.
5. "
cd lib/darwin-x86_64". This navigates to the second file with bad permissions.
6. "
chmod +x Vis". This fixes the permissions on the second file (which is also called Vis).
7. Exit Terminal. All fixed!