I know why. When I tried to download the game my Antivirus Defence refused to accept the download and prevented it, I had to override it. And usually I would not do that however I could tell this was an authentic game. Others may be getting the same. I'm not sure how it is caused but perhaps if you changed how the game can be installed or change the files so the browser will permit it. As it is I tried to install it again but the link for indieDB said it has expired so no files can be downloaded.