How to implement gravity in unity so that planets etc. attracted and flew in orbits and at the same time the code was as simple and efficient as possible?

Question

Android

The code was as simple and efficient as possible.
Ideally, as in the android game "orbit".
If you can write code, I beg you to spend 5 minutes and show the result, I will remember you for a lifetime.

Answer 1

class Magnetic()
+ Related Bonus: UnityMagnets