Strange, I also used Godot and eventually I had the same bug I experience right now with your game in Firefox. It says in the dev tools that it failed to create the render target after the loading screen and the screen stays black :/ Needed to create a new project and messed around with the settings until I got it right, but have no idea what change made the trick in the end... Old games I exported (a few weeks to months ago) were still playable though. Would be great if you could export as Linux executable as well :)