Fan is an item that interacts only with Paper player.
Every Fan item produces an air flow of a given length. If player is caught on the flow, they will be carried in a direction of the flow until the last air flow game cell, and then player fall is initiated.
If one Fan flow intersects with another Fan flow, second flow is getting the priority, and player is starting to move in the direction of a new air flow. Fan flows can be chained, but a Fan whose flow player has already ridden in the current chain is ignored, so two Fans cannot pass player back and forth forever.
If player travelling in the air flow reaches a Block (obstacle), player fall is initiated (game will end this flow one game cell before the obstacle Block).
If Fan flow reaches an obstacle exactly after one world cell after the Fan item itself, entering in such one-cell-flow will result in a player Stuck level fail.
If player is carried to the end of a flow that is oriented bottom-to-top relative to player's gravity, it will result in a player Stuck level fail, regardless of the way player got into the flow.