Really interesting game and addictive project! Love to see how boxes merge! Great idea 💡 would recommend to download!
Thats because i needed to enable an experimental feature at itch.io ("SharedArrayBuffer support — (Experimental) This may break parts of the page or your project. Only enable if you know you need it"). I don't know why Godot 4 need this feature. I have the same problem if i try to play using my phone web browser. Anyway, it's not a game bug that i can solve. Sorry.