There are lots and lots of fun shared sci fi and fantasy universes out there, some of which were carefully designed to be a shared universe from the start. George R. R. Martin's "Wild Cards" comes to mind. Plus of course all of DC and Marvel. Every fan fiction author knows the fun of picking a ready to go universe and going "what if this guy fought/loved that guy?" Sometimes setting up a template can be a really cool way to encourage growth, like an artificial coral reef.

But this specific one does seem like a complex starting point.