Beatbound Runner

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 responsive browser canvas game titled "Beatbound Runner". Use a full-screen 2D canvas with a fixed HTML HUD over it, dark neon arcade styling, and touch-friendly controls.

Visual presentation: The background is a vertical gradient from deep navy blue (#101d3b) at the top to nearly black (#080b17) at the bottom, with a sparse field of tiny dark-blue moving square specks. The lower portion has a muted blue ground/horizon region beginning around 58% of the screen height, plus a thin blue horizontal lane line around the runner's ground level. Keep the style minimalist, flat, glowing, and high contrast. The player is a glowing cyan circular character with a small dark eye, positioned at 22% of the screen width and at roughly 76% of the screen height when grounded. Give it a subtle idle bob and a squash/stretch effect when jumping. Obstacles are bright pink-red glowing vertical rectangular blocks of randomized width (roughly 34–52 px) and height (roughly 38–73 px), standing on the ground; add a small lighter pink highlight near each obstacle's top.

Game flow: Begin on a menu screen with the HUD visible. At the top left show the uppercase cyan brand on two lines, "BEATBOUND RUNNER". At the top right show a small uppercase SCORE label and score 0. Center a large bold title reading "JUMP ON THE BEAT", an instruction line reading "Press Space, tap JUMP, or click when the pulse reaches the ring.", and a rounded cyan START RUN button. Near the bottom center show a timing status with bold "Ready?" and the smaller text "JUMP WITH THE PULSE". The menu should have no obstacles and the player can remain off the active scene until starting.

On starting, reset score, combo, best combo, misses, elapsed time, obstacles, particles, and player physics. Hide the center menu and show a large circular yellow JUMP button at the lower right (112px by 112px on mobile, with a darker offset shadow). Keep the score at top right. At bottom left show "COMBO x[number]   MISSES [number]/3". At bottom center show the current timing result in uppercase, initially "LOCK IN", with the smaller line "JUMP WITH THE PULSE". On desktop, place the jump button about 38px from the right and bottom; on smaller screens use about 20px right and safe-area bottom spacing.

Core mechanic: this is an endless auto-running one-button platform/obstacle game where the character jumps in rhythm with a 120 BPM beat. One beat is 0.5 seconds. Draw a pulse ring at 72% of the screen width and 30px above the ground line. While playing, make the ring pulse from radius about 26 to 44, and briefly flash/grow it on beat events; use a blue ring normally and a yellow ring during the beat flash. Label it "BEAT" in small yellow text underneath. The player does not move horizontally; obstacles move left toward the player. Start beat scheduling after approximately two beats, play a repeating electronic beat using a triangle synth melody and kick/bass percussion if audio is available, and flash the ring on each beat.

Jump controls: accept Space, ArrowUp, clicking/tapping the canvas, or pressing the on-screen JUMP button. Only allow a jump while grounded. On jump, give the player strong upward velocity approximately -0.82 times screen height, with gravity approximately 2.15 times screen height per second squared, so the player arcs and lands automatically. Evaluate timing against the nearest beat phase: within 0.105 seconds is PERFECT, within 0.22 seconds is GOOD, otherwise OFF BEAT. A PERFECT awards 100 plus 10 times the current combo, increments combo, updates best combo, displays "PERFECT", and emits around 12 gold particles. A GOOD awards 50 plus 5 times combo, increments combo, updates best combo, displays "GOOD", and emits around 8 cyan particles. An OFF BEAT resets combo, displays "OFF BEAT", and emits around 5 pink particles. Every successful jump should use a cyan character squash/stretch burst.

Obstacle generation and collision: begin spawning on beat events after roughly 1.4 seconds (after the initial two beats, using the beat schedule). Spawn an obstacle just beyond the right edge at x = screen width + 40. Increase horizontal movement speed from about 270 pixels/second over time up to about 420 pixels/second. Usually spawn one block; on about 18% of spawns, add a second block roughly 24% of screen width farther to the right. Move all blocks left. If a block passes completely behind the player, add 10 score. Detect collision between the player's approximately 36px-wide, 48px-tall body and a block, but only count it when the player is grounded, allowing a jump to dodge it. On collision, increment misses, reset combo, display "DODGE FAILED", emit about 10 pink particles, and remove/move the hit block away. After 3 misses, end the run.

Scoring and end state: update the top-right score continuously. Successful rhythm jumps award the timing points; passed obstacles add 10. Track combo and best combo. When the run ends, hide the JUMP button and show the center overlay with title "RUN ENDED", subtitle "Score [score] · Best combo [bestCombo]. Keep the beat and try again.", and a rounded button labeled "RUN AGAIN". Change the bottom timing status to "Missed the groove". Pressing the run-again button resets and starts a new run; Space or ArrowUp from a non-playing state should also start/restart.

Particles are small square cyan, yellow, or pink sparks emitted around the player, flying outward with gravity and fading within roughly 0.55 seconds. Include subtle glow/shadow effects on the player, obstacles, buttons, and beat ring. Prevent page scrolling and support pointer/touch input. Use system UI fonts, uppercase labels, rounded pill buttons, and responsive sizing based on viewport dimensions. The game should be playable immediately in a modern browser and should degrade gracefully if sound cannot start until a user gesture.