Disclaimer: I'm a bloody beginner.
Where in the code would I start to introduce this concept?:
Any player can walk up on the inside planes of a giant cube, switching the gravitational direction.
Upon switching the player can walk, jump, shoot/throw on his plane as if it was the "correct" gravity , but other players remain on their gravity plane, walking, jumping and shooting with their own interpretation of what is down.
I fear Godot assumes there is only one gravity (pointing downwards) in many prebuilt functions that are commonly used in physics, player movement and so on…