In a scenario where the player moves freely along the walls of a tunnel (like this), what is the best way to move the player along the walls of the tunnel?
I'm using Unity3d game engine. I've tried to remove all gravity and apply relative downward force on the object on every tick. Pressing right or left key applies relative force on the x-axis. But the player object will not rotate along with the walls of the tunnel and hence wont climb. I can calculate tangent to the center of the circle inside the tunnel and rotate the player myself but that wont work with curved tunnels.