Sketch Duel

Cinevva's analyzer read this game's design doc and its source, then wrote the brief below. "Make your own" hands it to the game creator as your opening message, so you start from a real spec rather than a one-line idea.

Recreate “Sketch Duel” as a portrait-oriented, mobile-first 2D rhythm tapping game rendered with Three.js and an orthographic camera. The playfield should fill the screen and use fixed virtual dimensions around 100 units wide by 200 high, adapting to different aspect ratios while remaining portrait-like. Visually, despite the paper/sketchbook concept, the actual gameplay canvas is a very dark nearly black field: use a black background, a subtly lighter narrow central vertical panel, a faint inner glow, and a heavy radial vignette that makes the outer edges almost black. Add a very subtle paper/grain feel if desired, but keep the final visible treatment extremely dim and monochrome, matching the reference.

In the center, create a narrow four-lane vertical track. Use four lanes about 7 units wide with small gaps between them, bounded by faint dark-gray/ink vertical rails and lane divider lines. Extend the track from above the screen to below the hit area. Put a slightly stronger horizontal hit line near the lower portion of the track, around y=-74 in the virtual world. Notes are simple solid dark-gray rectangular blocks, approximately 82% of a lane wide and 4 units tall, with low opacity so they appear as subdued gray bars against the black panel. They fall vertically from a spawn point around y=105 toward the hit line at a constant timing-calibrated speed, taking about 1700 ms to reach it. Use a repeating eight-beat placeholder chart at 120 BPM, with notes assigned in this lane sequence (zero-based lanes): 1, 3, 2, 4, 1, 2, 3, 4, then repeat. Give each spawned block a tiny random rotation/jitter to preserve the rough sketch feeling. Notes that travel substantially below the hit line should be removed and counted as misses.

The player interacts by tapping/clicking horizontally within one of the four lane regions; determine the lane from the tap’s x-coordinate. Also support desktop keyboard controls: D selects lane 1, F lane 2, J lane 3, and K lane 4. On an input, find the closest unhit note in that lane by absolute difference between current time and its scheduled hit time. Judge it Perfect when within 70 ms, Good when within 130 ms, and Miss when farther away or when there is no suitable note. Perfect removes the note and awards 300 points plus 2 times the current combo, then increments combo. Good awards 150 points plus the current combo, then increments combo. A Miss resets combo to zero. Tapping outside the track should do nothing. There is no game-over or fail state: it is an endless/practice mode.

Place two faint, single-color procedural rough-drawing characters on either side of the lower playfield, outside the lane track: one around x=-38 and one around x=38, both around y=-14, facing inward toward the track. Each is a simple outlined sketch figure with an oval head, tiny eye, tiny mouth, neck lines, and a rounded roughly outlined body. Render them as translucent dark ink, approximately 35% opacity, so they are barely visible in the dark scene. Generate three canvas-drawn sprite frames for each character using multiple jittered stroke passes to look hand-drawn. On every beat, cycle each character through the three frames and give it a small synchronized bob; make the first beat of each four-beat measure slightly stronger than other beats. The left character faces right and the right character faces left.

Use a 120 BPM clock (500 ms per beat) starting after a short lead-in. Generate a simple metronome click with Tone.js after the first pointer or keyboard interaction enables audio: use a short membrane/sine-like click, with a slightly higher/stronger pitch on beat 1 of each four-beat group. Keep audio as placeholder metronome only. Schedule notes ahead of time so they are already falling when visible, while positioning each note from its exact time-to-hit for stable rhythm timing.

Overlay a minimal HUD at the top. It should show the title “Sketch Duel,” “120 BPM,” “Score: 0” initially, “Combo: 0” initially, and a judgement field that displays Perfect, Good, Miss, or a dash/blank state and fades after roughly 600 ms. Include the small instruction text: “Tap a lane — D F J K on desktop. Click/tap once to enable audio.” Use pale translucent white/gray HUD text with a subtle screen-like appearance, contrasting faintly against the dark canvas. Disable scrolling and browser touch gestures on the canvas, support resizing, and keep all visual elements sparse, low-contrast, monochrome, and sketch-like rather than colorful.