Rules used in this game

1. The end. Singles: each player has four bowls. The player leading the end places the mat (its back edge 2–6 m from the rear ditch), delivers the jack, then bowls first. Players alternate.
2. Pairs and triples. Pairs have two a side with four bowls each; triples three a side with three bowls each. The leads play all their bowls first, alternately, then the seconds (triples), then the skips. The leading team's lead places the mat and delivers the jack, and in each pair of deliveries the leading team bowls first. Every bowl counts for its team. In this game each team uses one set of bowls and one colour.
3. The jack. A delivered jack must come to rest at least 23 m from the front of the mat, on the green and within the rink. If it stops within 2 m of the front ditch it is moved back to the 2 m mark. A valid jack is then centred on the rink's centre line.
4. Improper jack. If the jack is not delivered properly, the opponent may move the mat and then re-delivers the jack, but the original player still bowls first. If the second attempt also fails, the jack is placed on the centre line 2 m from the front ditch, with the mat left where it is.
5. Touchers. A bowl that touches the jack during its original course (including after hitting another bowl) is a toucher and is chalked. Touchers that reach the front ditch stay live and are measured where they lie.
6. Dead bowls. A bowl is dead and removed if it enters the ditch without being a toucher, comes to rest wholly outside the rink boundary, leaves the green, or (when delivered) finishes less than 14 m from the front of the mat.
7. The jack in play. A jack knocked into the front ditch within the rink stays live. If it is driven out of the rink, over the side boundary, or rebounds to within 20 m of the mat, it is re-spotted on the T (the centre line, 2 m from the front ditch; just in front of a bowl lying there, touching it) and the end carries on. There are no dead ends.
8. Firing. Until a bowler has played two woods in the end, the weight meter turns back at draw weight: enough to run a yard past the front ditch on that green, never enough to fire. After that it runs on into the red firing band, speeding up as it goes, and bounces off full weight.
9. Scoring. When all eight bowls are played, the player with the nearest live bowl scores one shot for each of their bowls nearer the jack than the opponent's nearest. Distances are measured edge to edge in world space. If the two nearest opposing bowls are within 0.5 mm, the end is drawn and no shots are scored.
10. Green speed. A match is played at one green speed, from 11 s (heavy) to 16 s (very fast). It can be chosen, drawn at random for each match, or drawn at random and kept secret until the match ends.
11. Next end. The winner of an end leads the next; after a drawn end the same player leads again. Each end is played in the opposite direction, from a fresh mat.
12. Simplifications. Bowls are modelled as 127 mm circles in plan. Objects in a ditch stay where they fall and no longer collide. Other rinks are empty, so bowls may swing across them and return.