Zerdly

Pool & Billiards

A full nine-foot table with a two-stage aim, because an ordinary pot is only 0.70° wide. 5 tables: a frame against the house at 3 levels, a practice table, 6 proved called shots, two players on one device, and a daily run-out.

Racking up…

A thin cut costs you twice

An ordinary pot is 0.70° wide. Cue ball and object ball sixty centimetres apart, pocket sixty centimetres beyond, square on: that is the whole range of aim directions that pots the ball. It is why the aim here is two controls rather than one — a drag on a phone cannot deliver tenths of a degree, so the coarse step points the cue and the 0.05° fine step aims it.

Cut the ball and the window collapses: 0.28° at sixty degrees and 0.05° at eighty — a fourteenth of a straight pot. The tidy explanation, one over the cosine of the cut, under-predicts that by four times at the thin end, so what is published here is the measurement rather than the story.

And it costs power too. The object ball only takes the part of the cue ball’s speed pointing along the line between their centres: 1.00 of it straight on, 0.42 at sixty degrees, 0.08 at eighty. Rolling a ball sixty centimetres needs 4% of the dial straight on and 95% at eighty — and a shot hit that hard sends the cue ball most of the way round the table. That is the whole game: where the cue ball stops matters as much as what it hits.

The pockets are smaller than they look

A corner mouth is 114 mm across and a side mouth 127 mm, but the ball’s centre has to clear both jaws — so a corner pocket is really 57.2 mm of target for the centre of a 57.15 mm ball. It narrows again at an angle: the same pocket offers 23.7 mm to a ball running down the rail, because a mouth seen from the side is foreshortened before it loses the diameter.

That is not a difficulty setting; it is the arithmetic of a mouth and a ball, and it is why a corner pocket accepts a ball best along its diagonal. The house prefers a square approach for exactly the same reason, without being told to.

There is also a limit to how thin a ball can be cut at all, and it depends on distance: 68 degrees from fifteen centimetres and 89 degrees from two and a half metres. A cue ball close to the object ball can be cut less.

The house

Every shot the house considers is played out through the same physics and judged by the same rules you play against. There is no second implementation, so there is nothing it could know that you do not — and its hand shakes once, before the ball moves, never after seeing where it went.

Measured over 259 shots a level, it pots 30.5% on Easy, 43.6% on Medium and 62.5% on Hard. With its hand held perfectly still all three pot the same share, which is simply how often these tables have a pot at all — so what the levels change is how many shots it looks at and how steadily it delivers them, which is exactly what a difficulty is allowed to change.

The tables

  • 8-Ball — A frame against the house. Groups are open until someone pots, only the eight is called, and every foul is ball in hand.
  • 2 Player — The same frame with both players on this device. Turns hand over on screen; nothing leaves the browser.
  • Practice Table — No opponent, no groups and no end. The aim line is on, and nothing here touches your records.
  • Trick Shots — Six called pots, easiest first. One shot each, a named pocket, and every one proved makeable before it shipped.
  • Daily Table — One generated table for everybody, changing at midnight UTC. One turn: your run ends at your first miss.

Trick shots, and what the physics said about them

Circus trick shots do not survive a physically honest table, and that is a measurement rather than an opinion. A frozen line of three pots one ball, not three: the impulse passes through equal masses to the front ball and the middle ones barely move. A ball frozen to the rail is a lottery — it rubs the cushion all the way to the pocket, and whether it drops turns on a thousandth of a degree. A two-ball carry needs a fiftieth of a degree of aim, against a fine control that steps 0.05°.

So the preset is 6 called pots instead, easiest first, each verified and each carrying the width of its own window — from 0.62° down to 0.15°. That is a smaller claim than “trick shots” and it is the true one.

Local play

Everything runs in this browser. There is no sign-in, no leaderboard and no account: your settings, your bests and which Daily tables 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.

Questions

Why is the aim two separate controls?
Because one is not enough, and that is measured rather than assumed. An ordinary pot — cue ball and object ball 0.6 m apart, pocket 0.6 m beyond — has a window of 0.70°. A drag that rotates the cue about the ball with a 100-pixel lever arm moves about 1.75 pixels per degree, so a single pixel of pointer noise is most of that window. The coarse step is 1° for pointing the cue somewhere new and the fine step is 0.05° for settling on the pot: about 14 fine steps across an ordinary pot.
Why did that thin cut miss when I aimed it perfectly?
Because a thin cut has almost no window. At sixty degrees of cut the same shot is 0.28° wide and at eighty it is 0.05° — a fourteenth of a straight pot. The first-order explanation people give, one over the cosine of the cut, under-predicts that by four times at the thin end, so the numbers here are measured rather than derived from the tidy story.
Why does a thin cut need so much power?
Because the object ball only takes the part of the cue ball's speed that points along the line between their centres. Straight on, that is 1.00 of it; at sixty degrees of cut 0.42; at eighty, 0.08. So rolling a ball 0.6 m needs 4% of the dial straight on and 95% at eighty degrees — and a shot hit that hard sends the cue ball a long way. A thin cut costs precision and position at once.
Is there a limit to how thin I can cut a ball?
Yes, and it depends on how far away the cue ball is, which is not obvious. At the graze limit the object ball leaves at ninety degrees to the line the cue ball is travelling — but that line has itself rotated off the line joining the two balls, so measured the way a player measures it the most you can cut is ninety degrees minus that rotation. From 15 cm away that is 68°; from 2.4 m it is 89°. The house plays by the same rule, so it never tries a cut that does not exist.
Why do the pockets feel smaller than they look?
Because they are, by a whole ball diameter. The ball's centre has to clear both jaws, so a 114 mm corner mouth is 57.2 mm of real target for the centre of a 57.15 mm ball. It gets narrower still at an angle: the same pocket offers 23.7 mm to a ball running down the rail, because a mouth seen from the side is foreshortened before it loses the diameter.
Which pocket is easiest?
A side pocket is the wider mouth — 127 mm against 114 mm — but a corner pocket accepts a ball best along its diagonal, so the answer depends on where the ball is coming from rather than which pocket it is. The HUD prints the widest pot on the table in degrees so you can see it rather than guess.
What house rules does this table play?
Six, and they are stated because there is no single eight-ball rulebook. Break from behind the head string, and a legal break either pots something or sends 4 balls to a rail. The table is open until someone legally pots, and the groups follow from that rather than from a call. Only the eight is called. A legal shot hits one of your own first and then either pots something or drives a ball to a rail. Every foul is ball in hand, anywhere. And the eight early, in the wrong pocket, or with a scratch, loses.
Does the house cheat on Hard?
No, and it structurally cannot. Every shot it considers is played out through the same physics and judged by the same rules layer you play against — there is no second implementation for it to know something you do not. What the levels change is how many shots it looks at and how steady its hand is: measured over 259 shots a level it pots 30.5% on Easy, 43.6% on Medium and 62.5% on Hard. With its hand held perfectly still all three pot the same share, which is simply how often these tables have a pot at all.
Are the trick shots actually possible?
Yes, and each one carries the width of its own window. There are 6, easiest first, from 0.62° down to 0.15° — and each ships with a verified solution, because two of the first six layouts we designed turned out to have no solution at all. Circus trick shots do not survive a physically honest table: a frozen line of three pots one ball rather than three, a ball frozen to the rail is a lottery, and a two-ball carry needs a fiftieth of a degree. So these are called pots instead, which is a smaller claim and a true one.
What is the Daily Table?
6 balls scattered on the cloth, the same for everybody, changing at midnight UTC. One turn: your run ends at your first miss. Every day's table is generated and then checked — the widest opening pot has to be at least three fine aim steps wide before the day is used, so you never get a table with nothing on it.
What do follow and draw do?
Striking above centre sends the cue ball on after the contact; below centre pulls it back. Side spin changes the angle it comes off a cushion. The tip is bounded at half a radius from centre, because further out than that is a miscue on a real table and a route that offered it would be promising a shot the physics does not have.
How big is the table, and how hard is a full-power shot?
2.54 m by 1.27 m of cloth — a nine-foot table — with 57.15 mm balls. Full power sends the cue ball at 7 m/s, which is a real break and would roll about 111 m on open cloth if the rails were not in the way.
Can I play without a mouse?
Yes. The pads under the table step the aim coarse and fine, the power is a slider, and the tip control is five buttons. Every reading the drag gives you is printed. A route whose only control was a drag would be unplayable without a pointer, and on this route it would be unplayable with one.
Does reduced motion change the game?
No. It resolves each shot without animating the roll — the same fixed logical steps run either way, so the result is identical. It changes no rule, no threshold and no score, and the route follows your operating system's setting automatically.
Why is there no leaderboard?
There is no server and no account, so there is nobody to compare you with. Your bests, your settings and which Daily tables you have played live in this browser under this route's own keys, and clearing this game's data leaves every other Zerdly tool alone.

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