Ah well sorry to disapoint here, but this won't be Metal and Stars only on platforms, if you're looking for a Metal and Stars rebalance I'm pretty sure there are a bunch of Forks of that mod currently in development and if i remember correctly, Metal and Stars has like, multiple planets where the main challenge is based on surface properties (ring world and frozen world) so having it be on platforms would be killing their challenges
what I'm making is much closer to a space block, but instead of the premise being
"what's the minimum amount of things you need on a platform to win the game without ever touching a surface ?"
It's more along the lines of
"What if basically the entire game was based around space and the space platforms ?"
along with that, I'm also planing on making Nauvis just like any other planet, so instead of having linear research, once you're done with your starter "station" Neumann Prime (really a planet with similar mechanics to a station for technical reasons and indeed a reference to M&S)
You can then choose to what "Shattered planet" you'll be going (not as in infinite space routes ofc, as in the base game planets that have been shattered)
and with each of those bundles of space locations, you can get 2 kinds of science packs
while some of these packs share their name with base game packs, the tech tree has been altered so much that they might not unlock what their base game counterparts usually unlocks (either because you've already got said research, or because it has been tied to another pack)
-Logistics and metalurgy for Vulcanus
-Manufacturing and Nuclear for Nauvis
-Chemical and Biological for Gleba
-Military and High Tech for Fulgora
If I manage to balance things right, the player should have to choose which location they want to take over first, without having any outright better option
currently I've got each kind of asteroid for the 5 planets of the base game fully done, but I have yet to implement any space route or location
The only thing I'm truly done with is the start, to get the player to space, via space science packs and propulsion science packs
so yeah, sorry for the wall of text, all that to say, even if this might not have been what you were looking for, if you enjoy working with space platforms like me. This might still be a cool mod to try out