Could you be more specific when you say you can’t open it?
Are you able to download it properly? Export it’s files to another folder? Is the game crashing when you try to open the executable file? If so, do you get any errors?
If there’s something wrong with the game itself, only the developer will be able to help you, so it would be best to contact them. However if the problem comes before you open the executable file, maybe we can find a solution here.