Hello, I recently downloaded this game today and had the same issue, but I found the fix under his blog on this website. I tried the demo version first and it worked and I was able to play the actual game!
These are the instructions from his other blog:
You must allow execution by passing Apple security, to do this right-click on the game, then run and finally run anyway.
Another way to do it is as follows:
Go to System Preferences -> Security & Privacy -> "Run Anyway" -> (Enter your password)