What exactly are the limitations that prevent this game from working in Firefox to the point where they need a "please download Chrome" banner? Just curious, I thought WebAssembly and WebGL were pretty competitive these days.
Chrome seems to have a more full-featured shim layer for handling older graphics drivers.
I have a netbook that Firefox won't even try to launch WebGL on. Chrome seems to run WebGL just fine, though shaders with more than about twelve instructions fall off a performance cliff.
(Add one multiplication operation over the limit, and performance decreases twentyfold. Keep the new line, but delete any other single line of code in the shader, and performance goes back to normal.)
Not sure how true this is, since both Chrome and Firefox use ANGLE as their default WebGL backend (at least on Windows).