It's not my job to sort out any tech related issues of course, but I do see false positives quite a bit when it comes to indie games. Even Ren'Py games get detected as false positives by some very aggressive anti-virus softwares.
The file is an installer for a game made in the Game Maker engine and my anti-virus (Avast) didn't detect anything. What might have thrown off your anti-viruses is that it's an installer and not the actual raw files.
If this weren't the in-house Gamer Maker installer I personally wouldn't have played the game either, so I recommend the author to not use the installer or also add the option to download the files directly.