This is a brief overview of how Modders have made this a whole new and improved game.
Mods listed with credit to the creators:
OPM: https://forum.kerbalspaceprogram.com/...
Minor planets expansion(addon for OPM): https://forum.kerbalspaceprogram.com/...
Kcalbeloh system pack:
https://forum.kerbalspaceprogram.com/...
Community tech tree: https://forum.kerbalspaceprogram.com/...