Rotation Pool , sometimes called rotation or 61, is a pocket billiards game , requiring a standard pool table, cue ball and triangular rack of fifteen pool balls, in which the lowest-numbered object ball on the table must be always struck by the cue ball first, to attempt to pocket (pot) numbered balls for points.

The object of the game is to score the most points, by pocketing higher-scoring balls than the opponent(s). A frame (individual game ) is won when a player or team reaches a number of points (usually 61) that makes it impossible for the opponent(s) to win. A match may consist of multiple frames (e.g. a race to 10), or in multiple rounds of multiple frames (e.g. three rounds of best 2- out -of-three), as in other types of pool.

Points are scored by pocketing the object balls on the table; the number of points awarded is equal to the number printed on the ball pocketed; for example, pocketing the 4 ball scores the player 4 points. In a two-player or -team game , the frame is over when a player or team has 61 or more points, although frames tied (drawn) at 60 points can occur (in which case the player who last legally pocketed a ball is credited with a bonus point and declared the winner). More than two players or teams can play, with the winning score being recalculated (whatever number will mathematically eliminate other players from outscoring the leader). For example, the 61- point mark is determined by taking the sum of the values of all fifteen balls, 120, divided by number of players, 2, to yield 60, then adding 1 to ensure a definite winner (other than in the event of a tie at 60, for which see above ).

Set up
At the beginning of each frame , the balls are racked in a triangle as in eight-ball and other games using fifteen object balls, but in particular with the 1 ball at the front (apex) of the rack , on the foot spot , the 2 ball on the right rear corner (from the vantage of the racker) and the 3 ball at the left rear corner (as in kelly pool), and the 15 ball the one with the highest value in the center; all other balls are placed randomly, and all balls must be touching. In informal British play, it is common to push the rack forward farther so that the 15 ball, still in the center of the rack , is resting on the foot spot . (See illustration at top of article.)

Game play
The primary rule of the game is that the lowest numbered object ball on the table at any time is the "ball-on" and must be struck first (including on the break shot a side break is a foul ), regardless of the player's intentions of which ball to actually pocket . Players may use the lowest numbered ball to pocket other (e.g. higher value) balls. Consequently, fifteen-ball not being a call - shot game , points are also counted if a ball is unintentionally but legally pocketed (a "fluke" or "slop shot "). A player's turn at the table continues until a shot fails to legally pocket a ball, a foul is committed, or the frame concludes.

Safety play is rather strictly limited in rotation . If a player legally pockets a ball, that player must shoot again; unlike in many games, there is no provision for a called, intentional safety play that pockets a ball. Safeties that consist of simply using the cue ball to drive the ball-on to the closest cushion , without contacting another object ball in the course of the shot , are limited to only two such shots per player per frame . Other safeties are unlimited, provided that the lowest numbered ball is of course struck first and either at least two object balls move in the course of the shot , or the ball-on is driven to a cushion that is not the closest to it.

If a foul is committed (other than a foul break or cue ball foul , as detailed below ), the incoming opponent may either take the next shot or require the opponent to do so, with all balls as they lie in either case. If the exiting opponent's foul was scratching the cue ball into a pocket or off the table, the incoming player's shot is necessarily ball-in-hand , and must be taken from behind the head string (in baulk ), although the incoming player may optionally require the fouling opponent to shoot again instead, with ball-in-hand behind the headstring). Shots taken from behind the head string must cause the cue ball to cross the head string ; however, if the ball-on is behind the head string , the player with ball in hand (including a fouling player who has been forced to take the shot by the opponent) may optionally have that ball spotted on the foot spot before shooting. There is no point penalty for fouls Three consecutive fouls (i.e. on three consecutive turns at the table) by the same player is a loss of frame .

Fouls include:
Failure to hit the lowest-numbered object ball first (or at all)
Failure to make an open break on the break shot (incoming player may either accept the object balls as they lie and take cue ball in-hand behind the headstring and shoot from there, or demand a re-rack and shoot a new break shot )
Scratching the cue ball into a pocket or off the table (incoming player has ball-in-hand behind the headstring, though may force the fouling opponent to shoot)
Failure to either legally pocket an object ball , or drive any ball to a cushion
Knocking an object ball off the table (it is spotted; balls legally pocketed on the shot are not)
A third or subsequent one ball safety to the closest cushion (see above )

Team play
Two-player doubles (or larger) teams compete by alternating teams and alternating players within each team. For example, if teams consist of players 1 and 2 versus players 3 and 4, and player 1 breaks, turns alternate in the pattern 1 (breaking), 3, 2, 4, 1, 3, 2, 4, etc. I.e., the ending of a player's turn at the table ends that team's turn at the table. As in individual competition, a player's turn at the table does not end until a foul is committed or the player fails to legally pocket an object ball (or the frame ends).
Three consecutive fouls by a team player disqualifies that player for the remainder of the frame (i.e., if player 3 were disqualified in the above example, then subsequent play order would be 4, 1, 2, 4, 1, 2, etc.) Balls that were legally pocketed by the disqualified player are not spotted.
Informally, team play can also be conducted in scotch doubles format. However, the disqualification rule does not apply, and three consecutive fouls by the team are a loss of frame (otherwise, the team with the hypothetically disqualified player would have an advantage, in no longer having to coordinate two players).