What platform or web browser are you trying to play on?
There are multiple formats the game works in so I need to know where you’re encountering the error to help you.
I was playing on safari on my iPad. So it maybe wouldn’t have worked regardless. But it was on iPad.
Safari unfortunately doesn’t do a lot of web based things in the standard way so support is broken in it.
Firefox or chrome should work fine if you have access to them.
You can also download the .gb file and run it in a gameboy emulator to play the game.
I’m sorry that I can’t be more helpful.
thanks for telling me. I’ll save the game so I can play it when I have better software. The game does look great.