Zerdly

Darts

Aim, then stop the release meter on the line. The board measures how far your darts scatter and shows you where a spread like that is actually worth aiming — which is not always the treble 20. 6 games, a house at 3 levels, and a daily round.

Chalking up…

The best place to aim moves

Everybody aims at the treble 20, and for a steady thrower that is right. It is not right for most people. Working out the expected score of aiming at every point on the board, for a player whose darts scatter by a given amount:

  • a 3 mm spread — the treble 20, worth 52.7 a dart
  • 16 mm — still the treble 20, worth 20.7
  • 20 mm — the 19, 109 mm out, worth 17.8
  • 44 mm — the 16, 78 mm out, worth 13.3
  • 80 mm — the bull, worth 11.3

And it is a drift rather than a list of beds. The best point slides down out of the treble 20 as your spread grows, across to the 19, inward through the 16, and finally onto the bull. Past about 38 mm it is not on a treble at all.

The reason is the arrangement of the numbers. The 20 sits between the 5 and the 1 — the two lowest on the board, adding to 6 — while the 19 sits between the 3 and the 7, adding to 10. Miss a whole sector beside the treble 20 and you get 3 or 15. Beside the treble 19, 9 or 21. The 19 is two thirds more forgiving, and a treble ring is only 8 mm wide.

Your spread, and what it is worth knowing

The release meter decides how far your darts scatter: a clean stop is about 8 mm and the worst one about 52. Stopping early pulls the dart low and late pulls it high, so a bad release is something you can see and correct rather than bad luck.

The board measures that spread over your last 15 darts — about the point you aimed at, not about the average of where they landed, because a consistent pull is an error even though it is not a scatter. The ring on the board is where that spread says to aim.

It does not move every throw, and that is deliberate. A 15-dart estimate is honestly noisy, and following it exactly moved the ring on more than half of all throws. It only moves when the new point is worth more than a quarter of a point a dart.

The games

  • 501 — Count down from 501 against the house. Three darts a turn, and the last one has to be a double.
  • 301 — The same game, shorter — so a single bad turn costs a third of the leg rather than a fifth.
  • Around the Clock — 1 to 20 and then the bull, in order. A double skips one and a treble skips two, so the rings are worth the risk. Scored in darts.
  • Target Close — Close 20 down to 15 and the bull, three hits each. Spares score while your opponent is still open. Closing everything is not enough — you have to be ahead.
  • Practice — No opponent, no end. The board shows where your own spread says you should be aiming, and nothing is scored.
  • Daily Nine — Nine called targets, the same for everybody, changing at midnight UTC. One point for the bed, two for the ring you were asked for.

The finishes, and the seven you cannot have

Every checkout this route offers comes out of a search over the board rather than a table somebody typed: 162 totals between 2 and 170, each ranked by how likely its steps are to land in the beds they need, and each one played through the real rules in the test suite to prove it lands on zero legally. It finds the routes a darts player would recognise — T20 · T20 · bull for 170, T20 · T20 · D20 for 160, T20 · D20 for 100.

And it offers nothing at all for 159, 162, 163, 165, 166, 168 and 169, because those seven totals cannot be finished with three darts by anybody. That is a fact about the board, not a rule this route chose.

Local play

Everything runs in this browser. There is no sign-in, no leaderboard and no account: your settings, your 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. The board is 340 mm across the doubles, drawn from the same geometry that scores your darts.

Questions

Why is the board telling me to aim away from the treble 20?
Because for your spread it is worth more. The board is not arranged by value: the 20 sits between the 5 and the 1, which add to 6, and the 19 sits between the 3 and the 7, which add to 10. So a whole-sector miss beside the treble 20 scores 3 or 15, and beside the treble 19 it scores 9 or 21. Once your darts scatter more than about 17 mm, that difference is worth more than the extra point a 20 carries.
How is my spread measured?
As the distance between where you aimed and where the dart landed, over your last 15 darts. It is measured about the AIM POINT rather than about the average of your darts, which matters: a player who throws four centimetres low every time has a tiny scatter and a large error, and it is the error that decides where you should aim.
Why does the advice ring not move every throw?
Because a 15-dart estimate is honestly noisy — at a true 44 mm spread the middle eighty per cent of estimates runs from 37 to 50 — and following it exactly moved the ring on more than half of all throws. A marker that jumps across the board every time you throw is not advice, so it only moves when the new point is worth more than a quarter of a point a dart.
Can I throw a perfect dart?
No, and that is deliberate. A clean release scatters about 8 mm and the worst one about 52 — which is roughly the range between a good player and somebody who has just picked up a dart. A control whose top end was exact would have no skill left above it.
What does stopping the meter early or late actually do?
It pulls the dart, consistently — early is low and late is high — and it widens the scatter. The pull is the important half: a bad release that only scattered would be a lottery with a lever attached, and nothing you did would be learnable. One sweep takes 1.1 seconds.
What rules does 501 use here?
Straight in, 3 darts a turn, and double out — the last dart has to land in a double or the bull. Double out is a setting you can turn off. Going past zero, leaving exactly one, or landing on zero with anything but a double is a bust: the whole turn scores nothing and your total goes back to what it was when the turn started.
Where do the checkout suggestions come from?
A search over the board, not a table anybody typed. Every finish is built from the same geometry that scores your darts, ranked by how likely each step is to land in the bed it needs, planned for a 18 mm thrower — and all 162 of them are played through the real rules in the test suite to prove they land on zero legally. It finds the finishes a darts player would recognise: T20 · T20 · bull for 170, T20 · D20 for 100, S20 · D20 for 60.
Why can I not check out on 159?
Because nobody can. There are seven totals that cannot be finished with three darts at all — 159, 162, 163, 165, 166, 168 and 169 — and that is a fact about the board rather than a rule this route chose. The finish readout simply shows nothing there.
What is Target Close?
The cricket-style game, with its rules written out rather than assumed. Close 20 down to 15 and the bull by hitting each 3 times — a double counts two hits and a treble three. Once you have closed a number and your opponent has not, further hits on it score its face value. Closing everything is not enough on its own: you have to be level or ahead on points.
How does Around the Clock work?
1 to 20 and then the bull, in order — 21 steps. A double advances you two and a treble three, which is the only reason to aim anywhere but the fat part of the number. It is scored in darts thrown, so fewer is better.
Does the house cheat on Hard?
No, and it structurally cannot: it throws a dart and whatever is under the point is what it scores, through the same function your darts go through. What the levels change is the spread it throws with — Easy 44 mm, Medium 20 mm, Hard 9 mm — and therefore where it aims, because it takes the same advice the board gives you. Measured over 30,000 darts a level it averages 39.7, 53.7 and 94.7 for three darts, and takes a median of 73, 37 and 19 darts to finish a leg of 501.
What is the Daily Nine?
9 called targets, the same for everybody, changing at midnight UTC. Two points for the ring you were asked for and one for the right number in the wrong ring, so 18 is perfect. Every call is a real bed taken from the board, so there is never a target you could not hit.
Can I play without a mouse?
Yes. The arrow keys move the crosshair 8 mm a step, the space bar starts the release meter and stops it, and the pads under the board do the same thing with taps. Every reading the pointer gives you is printed.
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 rounds 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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