Want to backup a game and keep save data

I need to delete and reinstall a game on my MacBook Air because of a game flaw, but I have gotten really far and want to back it up to an external storage device, but I'm not sure how to save the game keeping all the save data.

What game? Some games put saved data in /Library/Application Support.
If that's the case just delete and reinstall. Make backups of the game's folder in case.

Star Wars the Force Unleashed

Look in ~/Library/Application Support for a folder by that name or the name of the distributor (ex. EA or Lucas), whoever sells it.
If you cant find Library, hold down Option and click on the Go menu.

Thanks. Working good and still have all my data