If you are receiving the error message on a Mac computer, please disable Gatekeeper, as this may be preventing you from opening the file. To do this, click the Apple logo on the top toolbar and select System Preferences. Now select Security. If the padlock in the bottom left corner of this screen is not open, click on it. You will now see 3 options for downloaded applications, they are: Mac Store, Mac Store and identified developers, and Anywhere. Please select Anywhere and then confirm your selection. Then try installing the game again. Please note: To be on the safe side, please follow these steps again, and turn Gatekeeper back on after the game is finished installing.