Find the Yellow route
The cited walkthrough places the Yellow Tower north of the chairlift and the Yellow Tunnel southeast of the tower. The tower receiver accepts five puzzle rewards.
Shape the key
Insert five rewards at the tower, take the blank key, and start with the cutter outside. Follow the arrow after each completed cut. The route uses five cutters and trends toward the tunnel entrance.
Open the tunnel
Reveal the final step
At the Yellow Tunnel, use the fully cut key in the slot on the right side of the entrance.
Walk inside after the door opens. The public “Big Tunnel” achievement is the confirmation.
The network connects major regions on foot; it is dark, so carry a light source.
