We probably should have let people chose multiple choices as that's what the game lets you do, as I suspect its not just about exploration.

But I think we'll do the obvious things like the discovery of jump points / systems, but also having hidden locations / items inside systems - maybe in an asteroid field, maybe cloaked in a nebula - that people can search for.

And if and when we add a new alien race beyond the already established ones, we could let first contact go to the person that first arrives in that system