Pool

Goal of the game

Each player must pocket all the balls of their group, the solids (1 to 7) or the stripes (9 to 15), then the 8 in the pocket they call.

How it works

• Break: the cue ball is placed behind the head string. A legal break pockets a ball or drives at least four balls to the rails; otherwise, your opponent re-breaks.
• Open table: after the break, the first ball legally pocketed assigns the groups.
• You keep shooting as long as you pocket a ball of your group.
• Fouls: cue ball pocketed, no ball hit, wrong ball hit first or no rail after contact. Your opponent then gets ball in hand and places the cue ball anywhere they like.
• The 8: once your group is finished, hit the 8 first and pocket it in the called pocket (gold ring; tap a pocket to change it). Pocketing the 8 too early, in another pocket or while committing a foul loses the game.

Controls

• Aim: drag across the table. With a finger, the movement rotates the cue; with a mouse, it points toward the cursor. Tap a ball to aim at its centre.
• Fine aim: turn the wheel, or use the ← and → arrows (Shift: faster, Alt: finer).
• Strike: grab the cue or the cue ball, pull backwards to set the power, then release. You can also drag the gauge and release it. On the keyboard: ↑ and ↓ set the power, Space strikes.
• Spin: tap the cue ball target. At the top, follow (the cue ball keeps going forward); at the bottom, draw (it comes back); on the sides, side spin, which changes the bounces. Tap the target twice to return to the centre.
• Ball in hand: drag the cue ball, then aim.
• While the balls are rolling, tap the table to speed things up.

About the AI

The AI plays on exactly the same physical table as you. For each ball and each pocket, it computes the ghost ball, then refines the aim by simulation (secant method) to account for deviations caused by friction. It then evaluates every combination of power and spin by full simulation: chances of success given its accuracy, cue ball position for the next shot, risk of fouls. It plays safe when no shot is worthwhile and chooses its position when it has ball in hand. The levels differ in the number of shots studied, position play and the precision of the stroke: Master level deviates by only a few hundredths of a degree.