I haven't been able to run this game. When I try to launch it through the itch desktop app, it just displays a black screen, and when I try to run index.html in a web browser, it shows a screen with two green squares.
You're probably trying to launch it locally from your drive? That will not work unless you run a local server. It's much easier to just run it directly from the game's page, using a compatible browser (basically any browser that can run HTML5 content should be fine).