The Triple Knock is a pinball bar on 6th Avenue — a bar with a room of machines rather than a restaurant. Pinball directories list around two dozen games here and it hosts regular tournaments, including a weekly knockout and a monthly women's tournament, open to players 21 and over.
Pinball listings record the venue as 21+ and note there is no kitchen. Machines and events change, so check the venue's own page before planning around a particular game or tournament.