Please read these instructions carefully and follow exactly. Apple continues to make launching non-App Store applications more difficult:

1. Click the link and download the game *.dmg file.
2. When the download is complete, open the download folder.
3. Double click the *.dmg file to mount it.
4. In the window that has popped open drag the game icon to Applications in Finder.
5. Open up Applications in Finder.
macOS 14 and earlier
6. Double click on the game icon.
7. A warning stating "[game] cannot be opened because the developer cannot be verified" will appear. Click cancel.
8. Control-click the game icon and click open from the menu. This time you will be given a warning and a choice to open the application. Click open.
macOS 15
(Yes, Apple has gone absolutely bonkers with its so-called "Gatekeeper" in macOS 15.)
6. Open Terminal (Applications → Utilities).
7. Type the following command and press Enter: sudo spctl --master-disable.
8. Enter your admin password if prompted. This will allow you to override Apple's blocking of non-App Store applications. Exit Terminal.
9. Click on the Apple menu in the top left corner and select System Settings.
10. Scroll down and click on Privacy & Security in the sidebar.
11. Under "Allow applications downloaded from" select "Anywhere".
12. Close the System Settings.
13. Back in Finder double click on the game icon.
14. A warning stating "[game] cannot be opened because the developer cannot be verified" will appear. Click cancel.
15. Control-click the game icon and click open from the menu. This time you will be given a warning and a choice to open the application. Click open.
[Note: You only need to do steps 6-11 once.]