The implementation is a bit jank because of my limited understanding of curves and the Path3D node at the time, so I don't recommend following this exactly.
- The player hits a trigger at the start of the Path which will "attach" them to a PathFollow node.
- Movements horizontal from the player are passed to the pathfollow node and its moved that many units accordingly
- The player cannot exit the path from the beginning (didn't need to implement this for the jam and designed the levels to make it not noticeable)
- The player cannot re-enter the path at the end upon exiting, the trigger is removed once the player exits the path
Hope this helps