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Escapement · A Milo Puzzle

Build the gears.
Let Milo out.

Every level is a board of pegs, a tray of gears and a crank on a mainspring. Put the gears on the pegs, then let the spring go: it turns the crank exactly so far, and every dial your gears reach has to stop exactly where the level asks. Land them all and the door opens for Milo.

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Level 8-12, Four O'Clock, running: a crank and four brass gears in a train, two dials marked A and B turning towards their marks, Milo waiting by his door
FOUR O'CLOCK — TWELVE TO ONE, BOTH CLOCKWISE
A solved level with its working shown: 2 turns × 12/12 × 20/12 × 6/18 = 1 1/9 turns backwards
WHY IT WORKS, MULTIPLIED OUT
Milo walking under two crushers, one lit red and down, while an escapement ticks the gears above round a tooth at a time
DEADBEAT — TIMING, NOT JUST TURNS
Level select: the tower's nine floors in a column, and a card for each level of the ninth drawing its board
NINE FLOORS, 108 LEVELS

Most of the rules fit in a paragraph

Teeth add up

Two gears mesh when their teeth add up to the gap between their pegs, so a twelve and a twenty fit pegs thirty-two apart, and anything closer jams. Every mesh turns the next gear the other way. A gear in the middle only passes the teeth along: it changes which way the last gear turns, never how far. Two gears on one peg turn as one, and their ratios multiply.

That is most of it, and the rest of the game is what you can build with it. You can turn the crank by hand before you wind, to see where things are going. When the spring runs down, a dial is on its mark or it is not — and when it is, the solved card shows you why, gear by gear, from the crank to the lock.

A part a floor

Up the clock tower

  • Mesh — one lock, a few pegs, and the teeth that fit between them.
  • Pegs — more pegs than a train needs, and a longer wind.
  • Idlers — ratchets that turn one way only, and dials that want so many turns.
  • Ratios — stacked gears, and ratios that multiply.
  • Lifts — a rack rises a tooth for each tooth that turns past it, and from here Milo walks through the machine while it runs, under crushers that are only safe while their dial is lit.
  • Belts — reach across gaps no gear can span.
  • Bells — cams, and a differential that adds two turns together.
  • The Great Clock — an escapement lets the machine move a tooth at a time, and the last level sets the tower clock to four.
  • The Winding Room — a worm that turns its gear one tooth a turn and never the other way, and a planetary that adds two turns unevenly.

Each level has three stars: one for solving it, one for doing it in as little brass as the cheapest way, and one for its challenge. Many levels can be built more than one way, and the game keeps count of every build you find. Stars and builds dress Milo in hats and coats and cast your gears in new metals.

There is a new machine every day, the same one for everyone. Once you reach the ninth floor, the foundry opens and casts new machines without end.

Level 9-10, Orrery: a worm screw on the crank turning a gear, and a planetary box beside it
ORRERY — THE WORM AND THE PLANETARY

A lock is on its mark or it is not

Every level is proved

The rules are worked in exact fractions, never rounded, so nothing lands a hair off and passes. Before a level ships, a search tries every way its gears could go and proves it can be solved, that its par and its challenge can be met, and how many different builds solve it. The same search runs in the game when you ask for a hint, and it starts from what you have built: first it says which dial is off and by how much, then which peg to change, and last it places the gear itself.

Nothing on the board is a picture. Every gear, dial and belt is drawn by the GPU as it turns, and every sound is synthesised as it plays.