Bowling

A straight ball cannot strike

This is the fact the whole route is built on, and it is a fact about the geometry rather than a rule anybody chose. Pins stand 12.00 inches apart and are 4.77 inches thick, so the gap between two of them is 7.23 inches. The ball is 8.50. It cannot go between them, so it deflects — and a ball arriving square deflects away from the corners instead of driving through the rack.

Measured over every board a ball can be thrown down, at five speeds each:

• a straight ball, aimed anywhere — nine pins is the ceiling
• the pocket, arriving square — seven, leaving the 5-8-10
• the pocket, arriving on an angle — ten

That is the entire argument for hooking a bowling ball, and it is why this route has a hook control rather than a difficulty slider.

Why the ball hooks, and why a slow one hooks further

A lane is conditioned at the front and left dry at the back — here the oil runs 40 feet and the grip goes from 0.04 to 0.2. A bowling ball is released rotating about a tilted axis and under-rotated, which means its contact patch is SKIDDING sideways across the lane. Friction acts against that skid, and on the dry boards there is enough of it to turn the skid into a change of direction.

Nothing about that is scripted. The ball hooks because it is slipping, and it stops hooking because it has run out of slip — at which point it rolls, and travels in a straight line at whatever angle it has earned. A slower ball gives the dry boards longer to work, so it hooks about three times as far as a fast one, and arrives steeper. That trade is the game.

The pocket is on board 23

Not board 20, where the head pin is. The pocket is the gap between the 1 and the 3 for a right-hander, and the mirror of it for a left-hander. Arriving there on an angle takes out the 1, the 3, the 5 and the 9 with the ball itself while the rest scatter — and the corner pins mostly fall by being struck by other pins coming off the kickbacks, the hard partitions down each side of the pin deck. Leave those out of the model and a pocket hit stops carrying, which is exactly what happened the first time this was built.

The games

• Full Game — Ten frames, scored properly — strikes, spares, and three balls in the tenth if you earn them. The whole game.
• 5-Frame Quick — Half a game, with the last-frame rule applied to the fifth. A perfect one is 150, and there is nowhere to hide a bad frame.
• Practice — No score, no end, and the ball's path drawn before you throw it. The place to find out what your hook actually does.
• Challenge Spares — Ten set leaves, one ball each, getting harder as they go — from a corner pin to the big four. Scored in spares made.
• Daily Series — The same ten leaves for everybody, changing at midnight UTC. One ball each, one go a day.

The scoring, exactly as it is applied

10 frames, two balls each, and a strike ends the frame at once. A strike is worth ten plus the next two balls; a spare is ten plus the next one. The last frame is the only special case: clear the rack and it is racked again inside the same frame, so three balls are possible there — and those extra balls earn no bonus of their own, which is why a perfect game is 300 and not 330. The suite bowls a real perfect game through the physics, twelve deliveries, and checks the total.

A pin cannot be counted twice, and that is structural rather than checked: a ball reports which pins FELL, the rules require that set to be a subset of the pins that were standing, and they are then removed. There is no arithmetic path that could count one again.

Local play

Everything runs in this browser: the lane, the pins, the scoring, the challenge generator and every sound. No sign-in, no leaderboard, no account. Settings, bests and which Daily rounds you have played live in local storage under this route’s own keys, and clearing this game’s data leaves every other Zerdly tool alone. Practice is not scored at all, so the drawn path can never reach a saved best.

Questions

Why can I not strike with a straight ball?

Because the ball is wider than the gap between two pins. Neighbouring pins stand 12.00 inches apart and are 4.77 inches thick, leaving a gap of 7.23 — and the ball is 8.50 inches across. So it cannot pass between them; it deflects. A ball that arrives square deflects away from the corner pins instead of driving through the rack. Measured over every board and five speeds, nine pins is the most a straight ball ever gets here. The same pocket hit arriving on an angle carries all ten.

Why does the ball curve at all?

The front 40 feet of a lane are oiled and the back end is dry — the grip goes from 0.04 to 0.2. A ball leaves your hand rotating about a tilted axis and SKIDDING sideways, which the oil lets it keep doing. When it reaches the dry boards the friction turns that sideways skid into a change of direction, and when the skid runs out it rolls straight again. Skid, hook, roll — none of it is scripted; it falls out of friction acting against the slip at the contact patch.

Does throwing it slower really hook more?

Yes, and it is the main trade in the game. A slower ball gives the dry boards longer to work on it, so it hooks further and arrives at a steeper angle; a faster ball reaches the pins with more of its skid unused. Measured on this lane, a ball at the slowest end of the dial hooks roughly three times as far as one at the fastest.

Where is the pocket?

The head pin stands on board 20 and the pocket — the gap between the 1 and the 3 — is board 23. That is for a right-hander; a left-hander's pocket is the mirror of it, between the 1 and the 2, and the handedness setting flips which way your hook curves. Board numbers stay the same either way, because a lane that renumbered itself per player would be unreadable.

How does the swipe work?

Where you start the swipe is the board you stand on, where you finish is the line you send it down, how fast you swipe is the speed — and how much you CURVE the swipe is the hook. A straight swipe throws a straight ball. If a gesture is not your thing, the steppers underneath set the same four numbers a board at a time, and the arrow keys, brackets and space bar do the same job. The lane is 39 boards wide and speed runs from 5.5 to 9.5 metres a second.

What counts as a strike, a spare and a split?

A strike clears a full rack on the first ball; a spare clears what the first ball left. A split is marked when the head pin is down and the pins left standing are no longer one connected cluster, or a downed pin sits immediately in front of two that are still up — the 7-10, the 4-6, the baby splits and the 5-7 all qualify, while the 2-8 sleeper and the 3-6-10 wall do not. A split changes no score. It is a label.

How is the scoring worked out?

10 frames, two balls each, and a strike ends the frame at once. A strike is worth ten plus the next TWO balls, wherever they land; a spare is ten plus the next one. The last frame is the only special case: clear the rack and it is racked again inside the same frame, so you can throw three balls in it — and those extra balls earn no bonus of their own, which is why a perfect game is 300 rather than 330. The test suite bowls a real perfect game, ball by ball through the physics, and checks it comes to 300.

Why did a good hit leave the ten pin standing?

Because that happens, and for a reason the model reproduces rather than invents. A hit a fraction light carries nine and leaves the 10; a fraction high and it leaves the 5-7. The corner pins mostly fall by being struck by other pins bouncing off the kickbacks — the hard partitions down each side of the pin deck — so a shot that arrives slightly wrong loses exactly that part of the chain.

What is the difference between the five games?

Full Game is ten frames scored properly. 5-Frame Quick is half of it, with the last-frame rule applied to the fifth, so a perfect one is 150. Practice has no score, never ends, and draws the path the ball will take. Challenge Spares sets 10 leaves, one ball each, getting harder as they go. Daily Series is the same 10 leaves for everybody, seeded from the UTC date and changing at midnight UTC.

Where do the challenge leaves come from?

The leaves real first balls actually produce, rather than every arrangement of pins — there are 1,022 of those and almost none of them has ever happened. How hard a leave is counts the separate clusters it falls into, because a ball can only be in one place at a time: a single pin is easy whichever pin it is, and the big four is hard because it is two pairs at opposite corners.

Does the game run on a server?

No. The lane, the pins, the scoring, the challenge generator and every sound run in this browser. There is no sign-in, no leaderboard and no account. Your settings, bests and which Daily rounds you have played are kept in local storage under this route's own keys, and clearing this game's data leaves every other Zerdly tool alone.

Does the frame rate change the result?

It cannot. The shot is simulated to a standstill on a fixed logical step before anything is drawn, and the display then plays back a recording of what already happened. A slower screen shows the same shot with fewer of its frames.

Related interactives

• Pool & Billiards — the other route where the geometry decides the shot — a thin cut costs precision and power at once
• Darts — where to aim depends on how accurate you are, and the board shows you
• Rally Drift — grip that peaks and then falls away, which makes a slide a mistake or the fast way round
• Hover Racer — a boost worth spending in different places on different courses
• Zerdly Circuit Racer — the spec's suggested link, and the closest racing route to this one