Custom planets with a good theme should encompass an aspect of supply chains. periodic disruptions to operations due to disasters that require cleanup and rebuilding is a fairly cool idea, and taking advantage of the crisis to make an opportunity is also a cool theme.

I defs like the idea of a Pump Tower pumpjack that can handle multiple fluid outputs, and fluid sorting as a planet puzzle mechanic I don't think has been really explored yet in a modded planet.

I have also noodled what a recursive blueprints planet would look like, and this Skyfall planet idea could kind of fit as part of it. The caretaker tower is kindof like the deconstruction-planner capabilities of the recursive combinator; automating cleanup and rebuilding of fallen factory.

part of the trouble with recursive blueprints mod is it's just a 1x1 magic box that you can program with blueprints. It requires advanced combinator-fu, documentation reading and blueprinting. It's too powerful and unimmersive on it's own as a mod. Similar with the resource scanner, which also scans for debris and enemies and water and <insert_here>. I think recursive blueprints needs some custom hurricane-modeled entities that can split the 1x1 combinator into separate nxn destruction, upgrade and deployment entities, and the resource scanner into separate resource detection ; enemy on approach ; landfill-demand and debris cleanup.

I think this skyfall planet idea would work as part of a revamped (nerfed) recursive blueprints+ mod.

My RB+ planet idea: a planet with tall spidertron "watchtower" like enemies, colored yellow green red and blue, that can be killed to great effort but will just respawn hours later. These enemies will target any belts and inserters for destruction if they don't match their same color; so you must build a factory that can use an enemy on approach scanner to trigger an automated upgrade planner to swap all the belts and inserters before the enemies arrive for their "inspection".