Ok I might know one. the two dolls at the end credits of season 2 might be signaling the game
Dondaemun. let me explain
That game is like Korean musical chairs. Two people (The dolls) stand across each other And turn around so they cant see the players. then the other people walk in a circle around them. but at any point they turn around and if anyone is in their line of sight (straight) they are out. Now it goes until one is left but it might be round based due to the need for players.
And maybe the hanging people on the walls are signaling the game monkey bar.