Revolt hasn’t added federation because it can be a major complexity increase in the codebase, but apparently they might be allowing instance owners to integrate polyproto support (polyproto is a work-in-progress federated chat system). If you want a discord like interface for Matrix, Cinny exists. I personally prefer revolt in some ways as Matrix feels like it doesn’t fit the use case for discord as well.
Depends what counts as an in game currency, does a game where you earn currency in-game and spend it in-game count as an in-game currency? What about if players can trade it?
Funnily enough, there is an n-body mod for ksp1, which makes interplanet interactions more realistic (in fact, the mod has to slightly change the default system to stop the moons of Jool from slingshotting each other out) and allows advanced maneuvers like ballistic capture and lagrange points
Other games i know that do this are factorio (you are able to download the game as a zip, and it doesnt stop you from making as many copies as you desire)