The Big Walk 4166 puzzle is a coordinate problem, not a keypad code. Read 4166 and 1899 as the paired coordinates 41.66 and 18.99, then use the map or GPS to find a camouflaged button behind a rock.
Unlock the navigation tools first
This puzzle is not meant to be solved the first time the group sees the numbered signs. Complete enough puzzles to progress the Red Tower and open the map room near the starting hub. Inside are a floor map, portable map, compass, and other tools.
A separate GPS device can also solve the coordinate search. Published walkthrough testing places that device outside the Green Tower, where it can display the current coordinates while one player wears or carries it.
Read 4166 and 1899 correctly
On the map, use 41 as the longitude and 18 as the latitude to identify the main grid square east and south of the starting hub. The remaining digits add precision: 66 is roughly two-thirds of the way down that square, while 99 is almost at its far eastern boundary.
If the group uses the GPS instead, move one walker while another watches the readout and calls the direction. The target is a small button concealed behind a rock, so reaching the correct coordinate area is only the first part of the search.
Coordinate the button and reward
The hidden button and the frosted reward container are separated. One player must remain at the rock and hold the button while another waits at the original numbered structure to collect the reward when the container opens.
Bring walkie-talkies or use the in-game text system for the final timing. The official FAQ confirms that text works with walkie-talkies and follows the same range restrictions as voice, making it a valid way to coordinate the distant endpoints.