Wow, amazing! Definitely needs a 2x,4x maybe even 8x scale option though. Fortunately I could just zoom in with my browser, but it'd be nice not to have to.
The "outside" background on the second level would look cool with some parallax shifting. Occasionally fire would stop working, was that a mechanic or a bug? I played for about 10 minutes, unlocked the rocket arm, then got a bit lost. A map would be really useful.