Cool game.
When you have a bunch of lightning mushrooms, the game doesn't seem to ever end (or at least you can just sit idle for quite a while without any enemies getting through).
Also, the html file doesn't work. When you export a game to HTML, upload a zip with all the resulting files, not just the html file itself. You can also then set that file to "will be played in the browser", so it can be played directly on itch.io.