TITLE
The Combination

PROMPT
A safe-cracking game played by ear and by feel. A heavy 1920s safe door with a combination dial fills the screen; the viewer turns the dial, listening and watching for the faint tell of each wheel, to find a three-number combination, then throws the handle and swings the door open to see what the vault holds. Concept: intimacy with a mechanism; a game whose main feedback is subtle sound and tiny visual cues rather than a HUD.

Mood: tense, velvet-dark, luxurious, cinematic. Palette: near-black green #101412 background, bottle-green enamel door #1F3A2E, brass #C9A24B (dial, handle, hinges, lettering; highlight #E8CF8A, shadow #7A5F22), ivory #E7E0CF for numerals and text, deep red #8C2F23 for the indicator mark and felt. Dark page (the concept calls for it) with a single pool of lamplight on the door, falling off to darkness at the corners.

The safe (SVG): a door with bevelled edges, pinstriping and a gilt-lettered maker's name in an arc ("HOLLOWAY & STERN · FIRE & THIEF RESISTING · LONDON"), three heavy hinges, a five-spoke brass handle, and the dial: a knurled brass ring with 100 graduations (numbered every 10 in ivory) rotating under a fixed red index mark at twelve o'clock, with a domed centre knob showing a moving specular highlight as it turns.

Mechanism model (simulated faithfully enough to feel real): three wheels with gates; the combination is random each game (e.g. 34 – 71 – 12) with the classic sequence: turn left (counter-clockwise) at least three full turns then stop on the first number; turn right past the first number once and stop on the second; turn left directly to the third; then try the handle, which throws the bolts. The wheels are modelled as a real pack: the dial carries the third wheel, which picks up the second after a full turn, which picks up the first after another, and a wheel's gate can only be felt once the wheels behind it are already set. The viewer discovers each number by cues: as the dial passes a wheel's gate, the regular click of graduations is slightly different: softer, lower-pitched and with a tiny double "tick", and the dial has a barely perceptible visual notch: the red index mark trembles and the dial "sticks" for about 30ms (45ms on Apprentice; a slight resistance in the drag). Each time a wheel is picked up there is a single duller knock. A stethoscope gauge at the side (a small brass-rimmed meter whose sprung needle flicks with each click, swings far towards a red "GATE" zone with a double bounce at a true gate, and kicks the other way, towards "LIFT", when a wheel is picked up) gives a visual equivalent, so the game is fully playable with sound off. Difficulty levels: "Apprentice" (strong cues, gate width ±2), "Journeyman" (weaker cues, ±1), "Master" (faint cues, the exact graduation only, and one false gate that sounds low but gives no second tick). Changing the grade sets a new combination.

Interaction: drag the dial in a circular motion with mouse or finger (angle from the dial centre, with momentum disabled for precision; the dial must feel weighted: slight smoothing), or use the left/right arrow keys (one graduation per press, Shift for five), or scroll over it. A notepad in the corner, on cream paper in pencil-style italic, records what the viewer has found ("First: 34?"), automatically pencilling a number when the viewer pauses on a detected gate, with the ability to rub it out. A "Try the handle" control (the handle itself): if the combination is wrong, the handle clunks a few degrees and springs back, the door shudders; if right: the signature moment: the bolts retract with three heavy thunks in sequence (visible bolt rods sliding at the door edge), the handle spins, and the door swings open on its hinges in 3D perspective (rotateY with a slow heavy ease, swinging past ninety degrees on large screens to reveal the door's thickness, the bolt ends in its edge and the boltwork, wheel-pack cover and a typed service label on its back; on phones it stops edge-on at the left), light spilling out; inside, on red felt shelves, is one of several randomly chosen contents rendered in SVG with a line of copy: a single pearl on a cushion; a stack of love letters tied with ribbon ("To be burned unread. — H."); a model ship in a bottle; a sleeping cat that opens one eye; nothing but a note reading "Too late. — M." Top-shelf set dressing (a deed box, ledgers) sits above. A timer and number of handle attempts are shown as a discreet engraved plate, and the result is pencilled on the notepad ("Opened in 0:43, 2 tries."). A brass "Lock it again" tag inside the vault swings the door shut, throws the bolts and resets with a new combination and new contents.

Sound (Web Audio; off until the viewer turns on the designed brass toggle marked "Listen"): crisp per-graduation clicks (short filtered noise ticks), gate ticks with lower pitch and a second soft click, a low room tone, handle clunks, bolt thunks with sub-bass thud, door creak (filtered noise sweep). Stereo panning follows dial direction slightly.

Typography: gilt signwriter capitals for the title "THE COMBINATION" in an arc above the door (SVG textPath; a Didone/wide serif stack with gold fill and thin dark outline, no gradients beyond a flat two-tone), instructions as a typed card slipped under a brass clip: "Left three turns. Listen for the one that sounds tired." Entrance: darkness; a lamp switches on with a filament flicker and the brass catches light; the dial gives one idle spin and settles at 0. Reduced motion: door opens with a cross-fade; no tremble (the gauge and sound still cue). Responsive: door scales to the viewport; on phones the view is a close-up of the door, cropped at the sides so the dial occupies most of the width for comfortable dragging, with the gauge and Listen switch directly beneath and the notepad, plate, grades and card below; when the combination is right the view pulls back to show the whole safe before the bolts go.

DESCRIPTION
A lamplit, velvet-dark room with one object in it: a bottle-green enamelled Holloway & Stern safe with gilt pinstriping, three brass hinges, a five-spoke handle and a large combination dial. After a filament flicker the lamp comes on and the dial gives one idle spin to zero. The viewer cracks a random three-number combination by intimacy with the mechanism rather than by reading a display: every graduation clicks, but the gate of the wheel being worked sounds lower, softer and doubled, the dial drags for an instant, the red index shivers and the needle of a small stethoscope gauge leaps. A notepad quietly pencils in each number when the viewer rests on it. Throwing the handle on a wrong setting gets a clunk and a shudder; on the right one the three bolts thud back one by one, the handle spins, and the heavy door swings open in true perspective, showing its thickness and boltwork, onto felt shelves holding one of five small stories: a pearl, a bundle of letters, a ship in a bottle, a sleeping cat, or a card that says "Too late. — M."

VISUAL TECHNIQUES
- Layered inline SVG artwork for the safe frame, door, dial, handle, gauge, vault interior and five vault contents, all in the six-colour palette
- Dial split into fixed and rotating layers: a rotating graduated band with 100 generated ticks, ivory numerals and a knurled brass ring, under fixed lighting gradients, with specular highlights and soft glints that travel across the domed knob as it turns
- Real CSS 3D door: front face, back face with boltwork and an edge face with bolt ends, assembled with preserve-3d and swung on its hinge line with rotateY under perspective, using a slow heavy cubic-bezier ease
- Bolt rods that slide inside clipped ports across the door seam into brass keepers on the jamb
- Simulated three-wheel pack with pick-up play between wheels, gates, tolerances per grade and a false gate
- Spring-damper needle physics for the stethoscope gauge, driven by impulses from clicks, gates and pick-ups
- Web Audio synthesis: band-passed noise ticks, pitched-down double gate ticks, pick-up knocks, sub-bass bolt thunks, handle clunks, a resonant noise-sweep creak and a low room tone, with slight stereo panning by direction
- SVG textPath gilt signwriting with block shading for the arched title and the maker's name
- Lamp-pool lighting built from radial gradients, a corner vignette, faint striped wallpaper and feTurbulence grain; light spilling from the vault with a screen-blended glow
- Paper, brass-plate and pencil textures in pure CSS: a typed card under a brass clip, a perforated ruled notepad with pencil write-in and rub-out animations, engraved plates with slotted screws
- Entrance choreography: stepped filament flicker, then a decelerating idle spin of the dial
- Reduced-motion variant: no flicker, spin, tremble or shudder, and the door opens with a cross-fade

INTERACTION MODEL
Drag the dial in a circle with mouse or finger (angle is measured from the dial centre; movement is lightly smoothed and settles on the nearest graduation), roll the scroll wheel over it, or focus it and use the left and right arrow keys (Shift for five graduations). Turning left three turns carries all three wheels; the viewer listens and watches for the tell of the first number, stops on it, turns right past it once to find the second, then left to the third. Resting on a detected gate pencils that number onto the notepad; touching a pencilled number rubs it out. The brass "Listen" switch turns sound on or off (it starts off), and the stethoscope gauge gives every cue visually, so the game is fully playable in silence. Clicking, tapping or pressing Enter on the handle tries it: wrong, and it clunks, springs back and the door shudders while the plate counts the attempt; right, and the bolts retract, the handle spins and the door swings open to reveal the contents and a line of copy (the cat opens one eye, and blinks if touched). The "Grade of lock" plate switches between Apprentice, Journeyman and Master, and "Lock it again" inside the vault closes the door and starts a new combination.