Maybe make it multi somehow :D
Totally in brainstorm here... you could export some constructions into you own library and fight some other players structures. A bit like robot fights where you put the robot into an arena vs another team... and you spectate the result... I am sure some meta could emerge with differents tactics. No need to do it realtime tho. And you keep some scoretable of the bests :)
But I think the most enjoyable part is the construction and some story mode where you have to "make your way" and control de integrity of your structure(s).
I remember now for the split, but the thing is that it doesn't mean anything at the moment.
BTW, you could unlock some new pieces type each new level. That can be a thing to find when scavaging whatever you can :) So you'll got the progression flow and a goal at middle term. The piece could be hold by some boss tho'. The next level you'll need it to clear it or just defend yourself...