For Moonarchists I implemented a "cartoonish" physics for the sake of keeping the planets stable and easier to hit.
For each planet, I attract them to the black hole (and bullets are attracted to planets to make it easier to hit) https://github.com/renato-grottesi/moonarchists/blob/main/Game/Universe.gd#L85
Then I use Godot's impulse functions to interact with the physics engine: https://github.com/renato-grottesi/moonarchists/blob/main/Game/CelestialBody.gd#...