- Players: 2 or more; 4-6 is ideal
- Game type: Billiards, 9-ball
- Objective: Sink the 15 ball
The players first determine order of turns, which remains fixed during the game. The winner of the previous game, if any, begins first.
As in 9-ball, the lowest remaining ball (target) must always be struck by the cue ball first, regardless of what balls sink. A player's turn continues provided that the target is struck first and at least one ball sinks. Scratching or failure to hit the target ball first is ball-in-hand for the next player.
The goal is to sink the 15-ball when there are five or fewer balls remaining on the table. If more than five balls remain on the table and the 15 ball is sunk, then the 15 ball is placed back on table. If there are more than five balls on the table and the 15 ball sinks, a player's turn continues only if another ball sinks before the 15 ball. Also, when five or fewer balls remain, all shots must be called. The winner is the person who sinks the 15 ball when there are five or fewer balls remaining.
15-ball was created as a way of involving more players in a 9-ball-like game. It was created by the Queen Anne's crew on or about September 1999.