Sorry about this! It works fine on my Mac (Yosemite 10.10.5), so I'm not sure what the problem is here. It might be something didn't download right. I'd suggest deleting StarwardRogue.app in the game's install folder, and then doing a verify local file cache.
If that doesn't work, then if you can look in the RuntimeData folder under the game's install folder and pass over any error logs you find there, that would be appreciated.
Thanks!
Chris