Thanks for all your comments!
* Firefox has some serious performance issues with SVG unfortunately. I also included a stupid Easter egg that I think does not help with performance :)
* I didn't have time for sound, as I wanted to have no external assets and generate the audio as well as the graphics and didn't have time to work on that. Also, there is no sound in space, right?
* Ore sometime floats in the air because there is a discrepancy between the way the planetoid is rendered with smooth edges and the way it is represented as a polygon. The SVG uDOM should be able to help but current implementations are lacking so that's something I didn't have time to fix either. Let's just say this ore has some strange gravitational properties, and call it a feature.
* You get the ore that was directly inside the mining cone, so that when the planet collapses the ore set free outside your cone is lost. You can see the money brought by the ore that you get but I agree that it's not very visible. The idea that I wanted to implement for the gameplay was that you had to balance between mining safely, which could end up not being cost effective in the long run, and blasting through the planet to get to the core at the risk of losing a lot of ore.