TITLE Night Watch at Sorrow Rock PROMPT A small, atmospheric arcade game: you are the keeper of a lighthouse on a reef and you steer the beam. Top-down-ish view of a night sea on a full-bleed Canvas 2D. The lighthouse sits on a rock near the bottom centre (on phones) or lower left third (desktop); ships enter from the dark edges heading for the harbour mouth (two breakwaters with a red and a green light and a few lit windows, in the bottom-left corner), and can only see the rocks your beam has recently lit. Concept: light as the only game mechanic. Palette: night sky/sea #07131F, deeper water bands #0E2A3A, beam and lamp #F6E7A8, danger/wreck red #E2543C, sea-foam grey-green #7FA7A6. Dark page, hand-drawn feel: the sea is rendered as layered horizontal wave strokes that drift slowly; rocks are jagged dark silhouettes with a foam ring; ships are small detailed silhouettes (trawler, schooner with sails, steamer with smoke) with a faint lantern of their own, a lantern reflection and a short dotted heading tick. Mechanics: the beam is a cone (about 18° wide) that follows the pointer/finger angle with smooth inertia (spring-damped rotation with a capped turning speed so it feels like a heavy lens), or A/D and arrow keys. Rocks and fog banks are invisible in the dark apart from occasional foam glints, which come faster when an unwarned ship is bearing down on that rock. A rock must be held in the beam for a moment (about 0.4 s; a dashed outline draws itself round it) to be revealed; it then stays "remembered" for a few seconds, shown as a fading dashed outline with the rock's name in small italics (the Sisters, Widow's Teeth, Black Maggie…). A ship that comes within sight of a remembered rock charts it for good (her lantern answers with an expanding ring) and steers around it; an unlit ship sails straight on and wrecks (red flare rocket, hull breaks in two and sinks, a bell tolls, a broken red mast is left on the rock). Each ship safely in harbour adds to the log. Three wrecks end the watch. Difficulty ramps through the night: more ships, drifting fog banks that swallow the beam beyond them and slow the revealing of rocks behind, a storm phase with rain streaks (brightest inside the beam), heavier swell, shorter memory and occasional lightning that silhouettes the reef for an instant. A night lasts roughly 4 minutes, shown as a clock from 21:00 to 05:00 with the sky paling to dawn (#3B5368) at the end, when the reef becomes visible by daylight and the lamp is put out. Signature moment: the beam itself. Render it volumetrically: additive gradient cone with soft edges and faint lens shafts, dust/moisture motes sparkling inside it, the lit patch of sea showing wave highlights and true colours while everything else is near-black; when the beam crosses a ship its sails and wake light up and it casts a long shadow across the water away from the lighthouse (rocks cast shorter ones, fog banks a wide one). The lens flashes with a starburst and a long horizontal streak when it sweeps past the viewer's direction (straight down the screen). Typography and UI: a keeper's log rather than a HUD: a narrow paper-coloured (#E9E2CF) ruled ledger strip (right side on desktop, top on portrait phones) in Georgia italic with entries written as they happen ("02:14 — Schooner Mary Elspeth brought in. Wind rising."), a tally of ships home / ships lost in small caps, and three small lantern icons for remaining chances. Title screen: the lighthouse standing in darkness, the title "Night Watch at Sorrow Rock" in tall letterspaced serif capitals that are only readable where the idle rotating beam passes over them (text revealed by the light, each letter keeping a brief afterglow; the beam lingers over the title and can also be steered by the viewer), a schooner drifting through the dark that becomes the first ship of the watch, the keeper's standing orders already written in the log, and "Light the lamp" as the start control. End screen: the completed log page with a rating written in the keeper's voice, a signature and a Lights Board stamp, and "Keep another watch". Optional sound toggle (off by default): low sea noise, rain, a bell for wrecks, a soft horn for arrivals, distant thunder, synthesised with Web Audio. Touch: drag anywhere to aim. Reduced motion: slower sea drift, no rain streaks, no flashes. Pause when the tab is hidden; P (or the pause button) holds the watch. DESCRIPTION A night sea in near-black ink strokes, a red-banded lighthouse on its rock, and one heavy, warm beam that is the whole game. The page opens on darkness with the title lettered across the water in tall capitals that can only be read where the slowly turning lamp falls on them. Lighting the lamp starts a four-minute night from 21:00 to 05:00: trawlers, schooners and steamers come out of the dark edges with only a lantern to show for themselves, steering for the harbour mouth, and they will avoid only the rocks the viewer has held the beam on. Everything outside the cone is guesswork and foam glints; everything inside it turns to true colour, with gold wave-crests, sparkling motes, lit sails and long shadows thrown away from the tower. Fog banks swallow the beam, a storm brings rain and swell, and at the end the sea pales to dawn and the whole reef stands revealed. Beside the sea runs the keeper's ledger, where the hour, three lanterns for remaining chances and every arrival and wreck are written in Georgia italic as they happen; the night closes on the finished log page with the keeper's own verdict on the watch. VISUAL TECHNIQUES - Full-bleed Canvas 2D scene with device-pixel-ratio handling (capped at 2) and a pre-rendered background of soft deeper-water bands and vignette - Three-layer light compositing: a dark scene, a separately drawn "true colour" lit scene, and a half-resolution beam mask used both as a destination-in matte for the lit scene and as an additive volumetric glow - Soft-edged cone built from fourteen nested radial-gradient wedges plus thin shimmering lens shafts and an omnidirectional lamp halo - Shadows cut out of the beam mask with destination-out gradients: long diverging shadows behind ships, short ones behind rocks, wide soft ones behind fog banks - World-space motes and rain streaks that only light up when the cone passes over them - Hand-drawn sea of several hundred drifting quadratic and bezier wave strokes in rows, with gold highlight strokes that appear only in the light and swell that grows in the storm - Procedural jagged rock silhouettes with animated elliptical foam rings, self-drawing dashed reveal outlines and fading name labels - Vector ship silhouettes (trawler, gaff schooner, steamer) drawn in two palettes, with lantern glow, reflection, wake trails, funnel smoke and a break-in-two sinking animation - Title lettering drawn glyph by glyph, vertically stretched and letterspaced, existing mainly in the lit layer so the beam reveals it, with a per-letter afterglow - Lens flare (radial bloom, anamorphic streak, starburst rays) driven by the beam's angle to the viewer and its turning speed - Red distress flare with rising trail and wide additive glow, screen shake, storm lightning that silhouettes the reef - Dawn grading that lerps the whole scene toward #3B5368 with a pale band at the top of the sea - Paper ledger UI in CSS: generated grain texture, ruled lines, red margin rules, punched holes, SVG hurricane-lantern icons with flickering flames, entries wiped in as if written - End page with spring-eased entrance, ruled scrollable log, signature flourish and circular SVG text-on-path stamp - Web Audio synthesis: filtered brown-noise sea with slow swell, band-passed rain, inharmonic-partial bell, low sawtooth horn, rumbling thunder INTERACTION MODEL Moving the mouse, or dragging a finger anywhere on the sea, sets the direction the lamp should point; the lens follows on a damped spring with a limited turning speed, so it swings heavily and overshoots a little. A/D or the left/right arrow keys turn it by hand. On the title screen the beam turns by itself and lingers over the title, but the viewer can take it and sweep the lettering themselves; "Light the lamp" begins the watch. During the watch the viewer holds the beam on a rock for a moment to reveal it (a dashed outline draws round it and its name appears); the rock stays remembered for a few seconds, and any ship that comes within sight of it in that time signals with a ring from her lantern and steers clear. Ships that meet an unrevealed rock are wrecked with a red flare, a tolling bell, a red entry in the log and one lantern going out; ships that reach the harbour mouth sound a horn and are entered as brought in. Fog banks shorten the beam and slow revealing behind them, and the storm shortens memory and brings more traffic. P, Escape or the pause button holds the watch (resume with P or by touching the sea), the bell button turns the synthesised sound on or off (off by default), and the game stops while the tab is hidden. After three wrecks or at 05:00 the finished log page appears with the tally, every entry, and the keeper's verdict; "Keep another watch" starts a new night on a newly laid-out reef. With reduced motion the sea drifts more slowly, rain, lightning, shake and lens flashes are removed, and the game remains fully playable.