Group forms a circle and someone e.g. a leader calls the name of a player. Immediately the people either side of the named player turn to that person, form their hand into a gun and say “Bang!” The person named tries to ‘duck’ by bobbing down.
The slowest person to ‘duck’ or to say “bang”, gets ‘shot’ and sits down in the circle. Those who remain standing play as if they are next to each other (ignoring the people that are sitting down). The last person who got ‘shot’ calls the name for the next round.
The last two standing both win. Alternatively they can stand back to back and play out a duel.