I don't know how to fully mod the game however if you've ever played mindustry and can figure out how to mix the two games into one game it would be hands down best game of the year. Basically. You build a giant spaceship using materials that you collect and you run the ship as the classic dagger style guy (classic mode with shift boost from mindustry) and you build a giant flying hand crafted customizable top down ship that is all powered by a huge factory as you fight off hordes of other enemies and travel to numerous planets (the level system but on a new randomly generated planet but it's not levels and it's sort of free play but with materials) and you can build with friends, massive turrets, endless map size, and they are both written in the same code so they are compatible as well as having similar design styles (although mindustry is more smooth, sorry) and the ship customizability would be ridiculous if you've seen mindustry's vastness, then add different cosmoteer stuff and OOH BOI.
Mix mindustry and cosmoteer (IDK how to tho)