After further investigation I believe there's an issue with the signature. Probably what happened was that someone updated the app without resigning the application.
In any case, I got around this by directly using the jar file instead of opening the application the normal way. I'd recommend fixing this so that the game just works though obviously.
For anyone else who has this issue, you can either change your permissions to allow apps downloaded from anywhere which I don't really recommend for just this game, or run "java -jar <path to Cultris.app>/Contents/Resources/Java/cultris2.jar>"