A series of three simple geometric shapes—a circle, triangle and square—printed on a nondescript business card is an invitation, as fans of Netflix’s ultra-violent mega-hit Squid Game now know. And the results of RSVP-ing to this cryptic offer vary wildly.
https://www.adweek.com/convergent-tv/squid-game-inspired-an-app-to-drop-10000-of-these-cards-in-new-york-and-miami/