I think a great addition would be the ability to create custom stars, planets and moon. Name them, perhaps pick from a few optional designs and, of course, you can already adjust the attributes. In any event, super cool game.
Thanks for the feedback, I'm glad you're enjoying the game so far!
It's funny you should mention that, as I have recently been working on a tool to allow the creation of custom planets and moons in order to streamline development. Whilst this is initially for developers (allowing for many new planets and moons to be added soon!) I do like the idea of including this in the game for you all to play with if there's enough interest!