What is a video game that you'd love to play, but no one has developed yet?

Evochron. One dev, super dedicated to this concept.

So basically Anno 2307?

I haven't played Anno 2205, but what your describing seems a bit further in time than that game. The start of colonization of the Moon vs settling/trading with the full solar system.

Elite Dangerous has some of those elements, not quite what you're describing rhough