I've been recently trying to find games to pass the time with colleagues similar to
"The game" https://en.wikipedia.org/wiki/The_Game_(mind_game),
"Yellow car" http://www.yellowcargame.co.uk/pages/officialrules.htm
or "Mariah Carey challenge" https://www.unibetcommunity.com/forums/topic/20669-christmas-quotno-mariah-careyquot-challenge/The main principle is that the game should be offline, is always on and you should need as little equipment as possible in order to play.
Does something comes to your mind?