Rhythm Ultra

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.

Create a browser-based 2D rhythm game titled “Rhythm Ultra,” designed as a loud, dark Newgrounds/portal-era arcade prototype with original characters and vector/canvas art. Make it responsive to the full viewport and support desktop keyboard plus mobile touch.

Use a full-screen canvas with a dark stage backdrop. The menu background should show a deep blue/black vertical gradient, a large translucent glowing circular light near the upper-right, faint vertical crowd/light pillars across the lower half, and two simple cartoon performers behind the interface: the selected player on the left and a green-haired/bright-accented opponent called Portal Punk on the right. Draw performers from simple geometric shapes: circular faces, triangular hats or hair, bright shirts, stick-like limbs, and a handheld microphone-like black shape. Overlay a centered translucent near-black rounded panel with a subtle light border and blur/shadow. The panel contains a large cyan-glowing “RHYTHM ULTRA” heading, explanatory text, compact pill tags showing selected character, stage, and difficulty, and large stacked rounded buttons.

The main menu must offer Story Mode, Freeplay, Character Select, Stage Select, and Difficulty. Start with Mic Kid selected, Back Alley selected, and Normal selected. Character Select has three original characters: Mic Kid (white/light face, blue hat, red shirt), Street Blaster (warm tan face, orange hat, cyan shirt), and Spook Duo (pale face, purple hat, lime shirt), with Spook Duo initially locked. Explain that later weeks unlock the spooky duo. Stage Select offers three selectable themes: Back Alley (dark navy with cyan glow), Crypt Yard (dark green with pale green glow), and Glitch Void (dark purple with pink glow). Difficulty offers Easy, Normal, and Hard. Story Mode offers three weeks, each with two named tracks: Week 1 “Kickstart / Substreet” unlocked initially; Week 2 “Night Shift / Bone Rattle” locked; Week 3 “Portal Burn / Static Clash” locked. Locked options are disabled and visibly marked LOCKED.

Story mode starts a selected unlocked week, while Freeplay starts a generic “Freeplay Mix.” Starting gameplay resets score, misses, health, combo, notes, timer, and judgement. Render the selected player at the left side and Portal Punk at the right side over the chosen stage. The stage should use the selected theme’s gradient, a translucent colored glow circle near the upper-right, faint crowd-light pillars, and a dark floor band along the bottom.

The core rhythm mechanic is four vertical lanes centered across the screen. Each lane has a receptor at the bottom around y=585, represented by a white rounded square with one of the arrow labels ←, ↓, ↑, →. Notes are colored rounded squares falling downward from above the screen toward those receptors, with lane colors red, green, blue, and yellow and matching arrow glyphs. Spawn notes randomly in one of four lanes at regular intervals; do not assume authored charts or audio synchronization. Notes move downward at difficulty-dependent speeds: Easy 380 pixels/sec with 0.82-second spawn interval and a 76-pixel hit window; Normal 480 pixels/sec with 0.64-second interval and 64-pixel window; Hard 590 pixels/sec with 0.52-second interval and 52-pixel window.

The player hits lanes with ArrowLeft, ArrowDown, ArrowUp, and ArrowRight, or by pressing the four large colored touch buttons at the bottom labeled ← ↓ ↑ →. Only process one action per key press, not held-key repeats. Find the nearest active note in the pressed lane; it is hittable when its vertical distance from the receptor is within the difficulty hit window. A successful hit marks it removed, raises combo by 1, adds 350 points plus a precision bonus based on timing and combo points, restores 2 health, and displays judgement: “Sick” within 16 pixels, “Good” within 34, otherwise “Bad.” Pressing with no hittable note resets combo, increments misses, reduces health, and shows “Miss.” Notes that pass more than 110 pixels below the receptor are automatically removed, reset combo, increment misses, reduce health by the difficulty miss damage plus 1, and show “Late Miss.” Miss damage is 9 Easy, 11 Normal, and 14 Hard. Clamp health between 0 and 100.

During play, show a left-side HUD with SCORE, COMBO, MISSES, and a bordered horizontal health bar: red background with a green fill proportional to health. Also show the selected difficulty and current track under the bar, and the current judgement at upper-right. Overlay a small translucent control panel at upper-left with current track name, a short instruction to use arrow keys or bottom buttons, and RESTART and MENU buttons. Keep the four colored touch buttons visible along the bottom during gameplay.

A song/week is cleared when score reaches the difficulty goal: 4,200 Easy, 6,500 Normal, or 9,000 Hard. On a clear, show a centered translucent panel titled “WEEK CLEAR,” the score and misses, and buttons for MAIN MENU and PLAY AGAIN. In Story Mode, clearing a week unlocks the next week when available; after clearing Week 2 or later, unlock Spook Duo. Freeplay clears should be logged without story unlocks. If health reaches zero, stop play and show a black game-over presentation with a large simple white skull face on the left and bold red “YOU DIED” text near the bottom, plus a panel containing score, misses, track name, RETRY, and MAIN MENU. Maintain the game state for menu, playing, and game-over screens, and make all menus and gameplay responsive on both desktop and mobile.