Sorry for the delay, I'm not checking the game page so often lately! Anyway, about your problem:
I unfortunately can't try to execute the game directly on a Mac machine (not having one), so I would like you to try a couple of things before I try on someone's else Mac. First, try to make the game executable using the terminal. So, open it and navigate to the game folder, then write " chmod +x t a k e y o u r t i m e Alpha 0.5 (the exact name of the executable file you clicked on to open the game)". If you can't find the filename just type "chmod +x" while inside the folder.
Try again and please report if it works after that!
Thank you for downloading the game.