Rules of the Game
The majority of rules exist for safety reasons, designed to protect both rider and horse. These should be taught early so they become natural before players build up speed.

Safety Rules
These rules exist purely to prevent injury to horses and riders. They are non-negotiable at all levels of play.

Line of the Ball
The "line of the ball" is an imaginary line running along the line the ball is travelling, continuing indefinitely past its present point. Crossing the line of the ball could result in a dangerous collision — commonly called a "T-bone".
Players must learn to recognise the line of the ball at any moment and avoid cutting across it. Entry on to the line of the ball is only allowed at a very small angle, or far enough in front of play for it to be safe. How far is "safe" depends on the speed of players following the line.

Stopping / Turning on the Ball
Players must not stop on the ball (e.g. if they miss a pickup) but must continue on past it until it is safe to turn or stop. Stopping on the ball could result in the other five players careening into the back of the stopped player.
Players must also not turn on the ball while running over it or just past it — this could cause the other players to run into the side of the turning player. Players must check behind themselves first to see whether it is safe to turn or stop.

Crossing In Front of or Behind a Horse
When crossing in front of or behind another horse you must always leave a sufficient gap to prevent one tripping the other. If a horse has to lift its head over another horse's rump in order to turn, they are too close.
At higher speeds the required distance is greater. The player changing direction is at fault.

Contact Between Horses — Riding Off & Doubling Up
Physical contact is allowed between horses but only in a controlled fashion. The initial contact must not be sufficient to move the horse off its line of travel. Once contact has been made, pressure can be applied to move the horse — this is "riding off".
Doubling up is where two players position themselves either side of an opponent. Any movement of the middle player from their line of travel is not allowed, even after initial contact. "Sandwiching" (too much pressure) and "wedging" (two players slightly ahead forming a wedge that decelerates the middle horse) are both strictly illegal.