On a wall, there is a mix of many letters and numbers in differen...

On a wall, there is a mix of many letters and numbers in different colors. It seems unreadable for the moment but players have a flashlight and three semi-transparent colored glass tiles – red, blue and yellow. Sadly, when used with the flashlight, it does not reveal a hidden combination. To see the code, players have to use green glass tile which can be made with blue and yellow tiles.