Yes, it crashes a lot and yes, menu controls are awkward and fullscreen could be the default. But the gameplay is really solid and satisfying, graphics and audio are cool, so the most important part is done well, nice!
Yeah, I absolutely need to rework the menu controls. Next version of the sub-engine absolutely needs mouse menuing. I presume defaulting on fullscreen for HTML5 is normal? I have admittedly very little clue what I'm doing with HTML5 exporting.