
Jubilee line Treasure Hunt organized by Transport for London
The treasure hunt commemorating 25 years of Jubilee line extension.
The Underground Mysteries by Tokyo Metro in 2018
I saw a lot of passengers carrying the following bag when I was taking Tokyo Metro. I then googled it and understood they were participating in a game organised by the underground train company here (地下謎への招待狀). English version was available too besides Japanese.