PLANETS, they can make this game EVEN BETTER although i havent even bought and played the game yet
Different planets could be cool. Few different ideas I've considered with planets (that I can remember):
1) Letting the player "travel" to a new planets after achieving a certain goal/mission. Effectively treating planets like "levels". Problem with this is that people seemed pretty attached to their base construction/builds, so there would have to be a good reason for having them abandon it and start over.
2) Starting on a visually different planets for each new game. Different biome/theme types, i.e. forest planet, ice planet, etc. Would give some visual variety to replaying the game.
3) Keeping the game on a single planet, but adding more biomes to the current world generation so that it's not all just Mars-esque dirt. Again, visual variety. Sometimes hard to get drastically different biomes to look good next to each other. Would allow different ways of spreading out resources that you need to search for.
Just my thoughts about it :
1) This one should probably be implemented (if you ever really code it, I mean :D) on a different "game mode". Like there's the "mission mode" and the "infinity mode". It could fit in missions (Teraform several planets seems like a really cool mission to me, even if I have to "lose" hours to start fresh on another planet. Especially if it's a different biome, discovering things I don't know yet. It's still really rewarding !
2) Now this one is really a good idea. Just because the fact that it would be possible to have access to certain things in a gameplay, and totally other things on the others. Like : Being unable to build GTR and using only "renewable" energies. Using only several Biofuel because there's not enough components to build a solar panel or something else. I don't know, just throwing that out. It seems like a really good idea, especially if it's not only the "visual" of the game that changes. Seems kinda hard to code though.
3) This one seems good if the amount of resources are perfectly managed which would be quite difficult, I think. Still a really good idea, since it adds content and visual variety wouldn't be a bad thing to a game like this where you ultimately play a lot of hours.