An excellent idea, anyone who had something similar must be very clever! Well done!

Only gripe is that I would often hit space to start the level, only to remember that was the restart button, would be great if it toggled between start level and restart.

Cool game. Maybe a little simplistic, as not only the planets don't change size when you increase their gravity (Being how this usually works IRL) but also in most levels you don't need half of  the planets. Just a few well tuned ones get the rocket to destination.

Hmm, I recognize those planets... Great minds think alike :). Good job!

Great game bro:) Also try my game please