Commission 1: Mrs. Abara's pocket watch
Her third pinion (the small gear on the third arbor, one of the train's spindles) cracked and came out. Pick its socket, fit a pinion from the drawer, close the case. This is the game, not a video of it.
A dare, before you do the obvious thing. Try the 12. It jams, because 80 + 12 is 92 and those holes are 90 apart. Now put the 78 on the centre wheel. It meshes, the train turns, and the readout says the watch gains 5.5 hours a day. Every gear fits and nothing is broken. It's just wrong, and you'd be sending her late husband's watch home to a woman who winds it every morning.
Close it true and Mr. Oduya's railway watch opens right here. His third wheel is stripped, and there's no 75 in the drawer.
The whole rulebook is two rules
The plate draws the first to scale. The dial shows the second: your hands walking away from the true ones.
- The holes don't move. Wheel teeth plus pinion leaves (a pinion's teeth) have to fill the gap between two fixed holes exactly, and both parts have to share a tooth size. Coarse teeth are bigger, so fewer fit (the sum × 0.8). Fine teeth are smaller (× 1.2). Get the sum wrong and you can see it: the gears gap or overlap.
- The escapement doesn't lie. The escape arbor, the fast one at the end of the train, turns 600 times an hour, always. Every hand's speed follows back from there through the ratios.
That's basically it. Mr. Oduya's watch is where it clicks. A standard 75 driving a 10 turns it seven and a half times. So does a coarse 60 on a coarse 8. And 60 + 8 is 68, which is exactly what coarse teeth need between his holes (85 × 0.8). The master's margin note: "75 on 10 is seven and a half. So is 60 on 8."
Yes, it's arithmetic. The game does the dividing and draws the answer, so the actual skill is spotting two pairs of numbers that make the same ratio. If that sounds like homework to you, the demo above will tell you in two minutes.
A wrong watch still leaves the bench
You can't fail a commission. The case closes as long as every mesh turns. If a hand is off, the report card says by how much, in the words a customer would use: gains 2.8 h a day, loses 6.7 h a day.
Each watch has three stars. RUNS means the case closed. TRUE means every hand is exact. AT PAR means it's TRUE and you touched no more parts than the proof says you need.
The owners' notes are what keep it from feeling like a spreadsheet. Mr. Oduya has thirty-one years on the 6:40 and asks for one thing:
"The seconds hand has to be honest."
His drawer holds a plan that does exactly that. The seconds hand runs true to the beat. The minute and hour hands gain 2.8 hours a day. It runs, it gives him what he asked for, and it's still wrong.
Stuck? The margin note is free. Press it and the master names one concrete step toward a par plan. It doesn't cost a star.
Par is proved, not guessed
For every watch, a solver tries every plan the drawer allows. Par is the fewest parts touched by any plan that keeps exact time. No plan that keeps time touches fewer, because the solver already looked.
| Watch | Plans that tick | Plans that keep time | Par | Plans at par |
|---|---|---|---|---|
| Mrs. Abara | 2 | 1 | 1 | 1 |
| Mr. Oduya | 2 | 1 | 2 | 1 |
| Mrs. Haddad | 6 | 2 | 2 | 1 |
| Dr. Lindqvist | 8 | 2 | 4 | 1 |
| Mr. Okafor | 6 | 2 | 4 | 1 |
| Miss Varga | 16 | 4 | 7 | 2 |
commission plans par at-par closest-twin make-it-mesh exact-twin mesh-the-pair abara 1 1 1 TRUE@par TRUE@par TRUE@par TRUE@par oduya 1 2 1 won't run won't run won't run off haddad 2 2 1 won't run won't run won't run off lindqvist 2 4 1 won't run won't run won't run off okafor 2 4 1 won't run won't run won't run won't run heirloom 4 7 2 won't run won't run won't run won't run ✔ every commission proved; no naive hand keeps true time past commission 1
npm run sim), pasted as it printed on 2026-10-10. Its plans column counts plans that keep time. The four columns on the right are the naive repairers.Read the last row. Miss Varga's heirloom has 16 ways to make it tick. 4 of them keep time. 2 of those touch only 7 parts. Her job card explains why that matters:
"Nobody has opened this case since 1931. Everything you touch, she will ask about."
The proof script also runs four naive repairers against every watch: closest twin, make-it-mesh, exact twin, and mesh-the-pair. Past the first watch, none of them closes a watch that keeps time.
Six watches, one week at the shop
- Mrs. Abara's silver pocket watch: one cracked pinion. You'll fix it in a minute. The point is the wrong fix that also runs.
- Mr. Oduya's railway watch, and no 75 in the drawer. "Don't send it out to wait for one." This is the one that teaches tooth sizes.
- Mrs. Haddad's gold wristwatch, where the hour hand "points wherever it likes." The fault is under the dial, in the motion works: two meshes that bring the hour hand down to one turn in twelve.
- Dr. Lindqvist's dress watch goes to the opera, and it has no seconds hand. Nothing reads the fourth arbor, so you can speed up one mesh and slow another, as long as the whole train still makes 600.
- Mr. Okafor's field watch came back from a dig in a bag of sand. Two faults, a thin drawer, and the part you need is already in the watch on another arbor.
- Miss Varga's heirloom. Two broken parts, nine in the drawer, and everything above at once.
Six watches is a slice, not a long game. More on that below.
Honest gripes: what's thin, what's fake
- Nobody outside my own test runs has played it yet. The open question in my build notes is whether the tooth-size rule clicks by watch 2 or reads like homework. You'd be finding out with me.
- It's six watches. I don't know how long they take a stranger, so I won't guess.
- The full game needs a keyboard. Its title and report screens only move on SPACE, and the bench is laid out for a big screen. The demo above works on a phone. The game doesn't, yet.
- There's no level select. Once you close a watch, you can't reopen it until you've closed all six and the run starts over. A refresh mid-watch also drops the parts you've fitted (your stars are kept).
- Five of the six watches have exactly one plan at par. Each one is a lock with one key, not an open optimization.
- The sound is a few synthesized blips and a tick.
What's real and what isn't
This part is for the watch people. The numbers are a real going train's. A centre wheel of 80 into a 10, a third wheel of 75 into a 10, a fourth of 80 into an 8: 8 × 7.5 × 10 is 600 turns of the escape arbor an hour, which is what 18,000 beats an hour gives you with a 15-tooth escape wheel. The fourth arbor turns 60 times an hour, so it carries the small seconds. Under the dial, 10 into 30 and 8 into 32 make the hour hand's 1 in 12. And for two gears of one tooth size, the tooth sum really does fix the distance between their arbors. That's the whole first rule.
The bench isn't real. Three tooth sizes stand in for module. Wheels and pinions sit in separate sockets here, where a real movement has them staked together on one arbor. And no watchmaker fixes a watch by raiding a drawer of loose wheels for a ratio that happens to work. They'd order the part. KEEPS TIME borrows the trade's math. It doesn't teach the trade.
Questions
- Is it really free?
- Yes. No account, no ads, nothing to buy. It runs in your browser.
- Do I need to know anything about watches?
- No. The job card says how fast each hand must turn, and the readout does the math. If you can see that 75 ÷ 10 and 60 ÷ 8 are the same number, you have the skill it asks for.
- Can't I just try every part?
- On the first two watches, sure. The drawers are small on purpose. On the heirloom, most blind swaps jam, and 12 of the 16 plans that do tick are wrong.
- Can I get stuck?
- Not for long. The margin note always names the next step toward a par plan, and it's free. And you can't fail: a wrong watch still leaves.
- Does it work on my phone?
- The demo on this page does. The full game needs a keyboard and a big screen for now.
- Does it save?
- Your stars do, in this browser. Close both watches up top and the full game opens on commission 3, Mrs. Haddad's. Close one wrong and that's the result it keeps until you've been through all six, so use "Do this watch again" first.
Watch 3 is waiting: Mrs. Haddad is late again
She's been late twice, because her hour hand points wherever it likes. Fix the two watches above and the game picks up at her commission, with your stars already in the ledger. Or skip them and start at the top.
P.S. Of the heirloom's 16 plans that tick, 2 keep time touching only 7 parts. The margin note will walk you to one of them. Finding the other is on you.