Really nice idea and execution, had a lot of fun with this one.
Having to deal with the collapsing world while also collecting ore felt great, but perhaps got a bit stale towards the end. Maybe having other hazards like volcanic eruptions or earthquakes or something would fix this.
The graphics and sound were all good enough, didn't feel jaunty or anything with the animations and the explosion effects and noise were sufficient to add impact to the meteors. The slight curvature of the planet was a nice touch, though this could maybe have been emphasized a bit more to make more sense with the size of the world.
There were some bugs that I noticed as well, that could use fixing. I think you messed up the double jump detection a bit, as touching a wall seemed to give you back your jumps, not just the floor. This wasn't too abusable in game, as hugging the wall seemed to slow you down, but it's still probably a good idea to fix that. Also, dying didn't reset your rocket progress. Not sure if that's a bug, but if it isn't you should probably change it anyway. It felt like it was making the game easier, bug in a bad way. Giving your player the option to reset twice to finish the level is not a good way of decreasing difficulty, as this promotes repetitive gameplay.
Despite those relatively minor objections, this was a great entry, and I highly encourage you to pursue the idea further.