Firstly, I just want to say that I'm really impressed with the game so far and its great to see such an active continued development going on! Because of that, I'd like to bring one specific area to your attention, as I feel it may be quite easy to improve upon while providing a rather solid return.
Now, I really like the experience that smaller sized planets provide, such as the moon or planetoid classes. Also, for me at least, the small / normal / large options mix rather well with those. Real fast turn times too! ;)
Alas, with the other classes there really is no option at all to go for an actual small sized planet, let alone a tiny one. Even choosing "small" and doing a lot of rerolling only ever seems to end up with a planet I would at the very least still call "normal" sized. Yet sticking primarily to the moon / planetoid class would mean missing out on quite a bit...
As such, I'd greatly appreciate the addition of a smaller size option for the other classes as well. Could be in the form of a "tiny" size option perhaps? I'm quite sure that others would benefit from more options in that regard as well and hopefully it's not too difficult to add such an additional option. At the very least I wanted to bring it to your attention!