The anti virus is flagging it as a potential virus because not enough users have run it. This is a very common issue for indie game devs and most users know to just run the software anyway.

 If you're worried that this warning will deter users from playing your game, you can always make your games to run in-browser.

1. The player can do this :

Go to System Preferences:

Open "System Preferences" from the Apple menu.

Select "Security & Privacy."

In the "General" tab, you should see a message about the blocked app. Click "Open Anyway."

2.the developer can avoid this issue in the future by:

Signing the application with an Apple Developer ID.

Distributing the app through the Apple App Store.

(moved to the right category)

As an aside: do you know you're not supposed to use the site at your age? Check out the terms of service.