Character Controller with Relative Gravity?

I need an fps character controller that applies gravity based on the rotation of the actual player.
My goal is to have a room where the player can essentially walk on walls or the ceiling by applying a simple rotation.
So far, I have had no luck using pre-made assets, and I’ve got no idea how to make my own.

The Controller needs:
-A constant force relative to the players transform.up angle
-Basic fps WSAD movement and camera rotation
-No jumping. The game itself would be pointless if you could jump.

If anyone knows of such an asset, or better yet, can explain to me the process of creating one, it would be wonderful!

I recently had to do something like this and came across this thread

The title might sound off but scroll down and you’ll see the code that does what I think you need; just comment out the calls to jump. I added a C# translation to page 2 if you need it.