That I would consider a real Game Changer! Even if only a handful of the planets were open to exploration, I feel like that would attract way more people! For example only the earth like planets could be explored. That would still work!
Along with planet exploration, there would be more types of components and vehicles... like the ability to build structures and for example structures (like space stations and buildings on planets) would need special rooms to sustain their crew. That would add a new element of strategy.
Imagine landing on planet with your spaceship (that you obviously wouldn't be able to explore the planet with because gameplay) and releasing a small buggy with a bunch of armed crew in it and defences on the side; which brings me onto my next point new vehicle types.
These new vehicles would be like hovercraft's andor buggy's which would have to be significantly smaller than the spaceships they would be carried in and they would use different smaller components (and armour pieces)
than the spaceships.
This brings me to my next point new spaceship components. Here is some of my ideas
Garage (small) It would be able to store a land vehicle
Garage (medium) It would be able to store two land vehicles
Garage (big) It would be able to store three land vehicles
Airlock If two airlocks from spaceships (or spaceships and space stations) would meet, the ships would be docked together (or the space ship would dock at the space station) and it would allow for a number of things (I'll go deeper into that later). The airlocks would also allow crew from land vehicles to get back on board of their spaceship if they are alive and their vehicle destroyed.
(quick note land vehicles would use different weapons to the spaceships)
Landing gear The size of a reactor room (2x2) You'd need at least 3 of these for a spaceship to be able to land but that would give you only 50% chance of a successful landing (I'll go deeper into that later)
Gun factory This would be placed in buildings andor spaceships it would produce weapons for the crew of the land vehicles.
Armoury That's where the guns are stored; if a crew member dies his gun goes with him!
There would also be a lot of new features like selecting the type of spaceships and switching between offensive defensive and support modes for spaceships a spaceship on offensive mode would make the spaceship station in a selected part of the map until a hostile is in sight. A spaceship in defence mode will attack anything that attacks the building it is assigned to defend. A support ship would dock with other ships if they are low on power, crew, missiles andor cannon projectiles and then, the crew from the support ship would refill anything that the other ship needs including crew members.
Now you maybe asking Why would I implement thatland on planets well maybe you could mine for ore that you can trade for money and there would be alien creatures which would want to destroy your buildings and that's why you'd have to set up defences on the buildings as well as arming your crew and having vehicles in store.
(Quick note #2 you'd be able to place airlocks on buildings)
(Quick note #3 garages would be compatible with buildings but not space stations)
I hope you took some inspiration and as always I think the game is great. Post any things you feel like I might have missed in the comments.
I'm TheMegaMan, and I'm out!