A clockwork music box lies open in front of you. The pegs are bare, the gears are loose in the tray, and the chimes are waiting to be driven. Drag the gears into place and set every chime turning the way its arrow points — the movement closes, and the melody plays.

Cogchime is a puzzle game whose rules come entirely from real mechanical transmission. No randomness, no countdown, no move limit, no penalty for failing. The only pressure comes from the puzzle.

■ THE RULE IS THE PHYSICS
Two meshed gears must turn opposite ways. So a chime's direction is decided by the parity of how many bites separate it from the mainspring — that is not a game convention, it is what gears have always done. You do not need a tutorial. One look and you know.

■ LESS IS MORE
A surplus connection locks the whole mechanism: the moment a closed ring of meshes has odd length, the directions contradict each other and the whole group stalls, shudders and sounds a dull thud. The best solution is usually several pieces leaner than your first instinct.

■ ONE FINGER
Dragging is the only input: pull a gear from the tray onto a peg, slide it between pegs, drag it back to remove. No buttons, no menu trees.

■ 158 LEVELS ACROSS 14 CHAPTERS
Mesh — meshing and reversal; two bites restore the direction.
Reversal — an idler bends direction without touching speed.
Jam — a gear train is a chain, not a web.
Duet — one mainspring, several errands.
Spacing — three gear sizes; the distance that meshes is calculated, not guessed.
Ratio — an idler cannot change speed; compound gears can.
Belts — a belt is a long edge with no flip, joining shafts that never touch.
Annulus — an internal ring; wheels hugging its wall turn with it, a circular bus.
One-Way — a ratchet permits one direction only; a crossed belt turns it back.
Decks — between the plates, coaxial layers run their own routes.
Orbit — sun, ring and carrier add and subtract; fix two and the third is fixed.
Worm — a belt drives only under tension, and an idle shaft is a brake.
Ensemble — the finale: large movements where every mechanic shares the board.
Aftertone — the piece-limited challenge; finish with as few gears as possible.

■ DAILY CHALLENGE
A new movement every day, the same board for everyone on earth. Build your streak.

■ MOVEMENT CODEX
Every level you clear is drawn as a blueprint card from your winning board: drafting grid, peg positions, mesh construction lines, belt runs, captioned like a museum plate. Meet par and it is stamped with the brass Thrift seal. Open a blueprint and the gears turn; you can replay that level's melody — the codex doubles as a collection of chimes. Beat your record — or match it a different way — and the drawing is redrawn.

■ CRAFTSMAN'S NOTES
Clearing a chapter unlocks a page on where the principle you just verified by hand comes from in mechanical history: the Antikythera mechanism, the watchmaker's depthing tool, the twelve-to-one motion work behind a dial, the crossed belts of the line-shaft era, the winding pawl, the epicyclic train, the self-locking worm. Fourteen pieces, short and considered.

■ FREE, AND PAID
Free for good: 84 levels, Aftertone's 8, the Daily Challenge and two themes; Annulus's first two are open to try.
The one-time Full Unlock opens the other 66 levels, cards and notes included, and every chapter added later at no extra charge; no second content product will follow. Buying opens V8 and the finale; V9–V12 unlock in order.
Supporter's Chime, also one-time, adds the third theme only. No levels.

■ CLEAN
No ads, no subscription, no consumables, no random rewards. No account — nothing to register, nothing to sign in to. What you have unlocked plays offline; buying and restoring need a connection. Apart from feedback you choose to send, the game transmits nothing to any server.

■ CONSIDERATE
Three themes: Walnut, Drafting Paper, Gilt Lacquer. Sound can be turned off. Honours the system "reduce motion" setting. Interface and content text in 13 languages.