This might be dumb but try clicking the game window with the mouse cursor over it and then try dragging the mouse around.

If this doesn't work then I don't know what is going on. Due to security concerns I cannot capture the mouse if it is outside the game window, so try fullscreen.

Hi man, sorry about your difficulties. I have mainly made this for controller-support, and in specific the X-boxen-range of controllers (360 and Xbone).

To get the mouse to work you need the pointer over the game window. Try playing in fullscreen, maybe that will work. Also WebGL isn't satisfyingly supported in a few browsers yet so there might still be issues.

I will look into this, though. Thank you for letting me know.