🎹 Neon Tiles — Happy Birthday

A neon-styled 4-lane rhythm game built around the most-sung song on Earth — "Happy Birthday to You" — the chart was transcribed directly from sheet music and runs through the full four-line verse twice. Cyberpunk visuals with a cyan→magenta gradient palette, ambient drifting tiles on the start and game-over screens, and the Orbitron typeface turn the candle-lit classic into something the synthwave dimension can throw a party with.

🎮 How to Play

• Tap / Click — Tap tiles on mobile, or click them with the mouse on desktop.
• Keyboard — Use A S D F for the four lanes (left → right).
• Hold notes — For taller tiles, keep the key/finger pressed until the tile clears.
• Pause — Space or P
• Mute / Unmute — M
• Quick start / restart — Press D while any overlay is showing.

✨ Features

🎵 Real Score, Real Pitch

• 9 measures played twice (18 measures total per cycle), transcribed directly from sheet music — both repeats of the "Happy birthday to you / Happy birthday to you / Happy birthday dear ___ / Happy birthday to you" verse plus the final cadence.
• Every note plays at its actual pitch in C major across a clean octave (C4 → C5), with a single chromatic A♯/B♭ at m7 — the colorful "dear ___" lift the song is famous for.
• Tempo is ♩=90 in 3/4 time, with each game beat = one 8th note (333 ms) — the gentle waltz pulse keeps each "Happy birthday" phrase singable.

🎶 Hold-Heavy Waltz with Built-In Breath

• The chart is dominated by 2-beat 4분음표 holds rather than rapid taps — Happy Birthday lives in its sustained syllables, not in fast runs.
• The chart's signature "Hap-py" pickup (originally a dotted-eighth + 16th) is rendered as two clean 8th notes back-to-back, so the rhythm reads at a glance instead of requiring sub-tile precision.
• Long cadential notes have been shortened to leave a built-in breath: the m2 / m4 "to you" 2분음표 is now 점4분음표 + 8분쉼표, and the final m8 "to you" 점2분음표 is 2분음표 + 4분쉼표 — every line of the song ends with a tiny pocket of silence before the next.

🚀 Progressive Difficulty + Cycle Flash

• BPM increases by +12.5% per cycle (90 → 101 → 114 → 128...). The gentle base tempo means even cycle 3 stays in singable territory.
• Each cycle is also transposed up by a whole step (2 semitones), sending the birthday wish into ever-higher keys.
• Cycle transition flash: every new cycle pops up a centered banner — CYCLE 2 / ♪ +2 · ⚡ +12% — with a scale-and-glow animation, so the moment you survive into harder territory feels earned.

💢 Visible Miss Feedback

• Tap on empty space, hit the wrong tile, release a hold too early, or let any tile fall off-screen — all trigger a red flash at the relevant tile (and a circle pulse at the tap point), held for 450 ms.
• Plays a dissonant low buzz with downward portamento so misses are clearly audible.
• The game ends after the miss display, giving you a clear "what just happened" beat.

🎨 Polished Neon Visuals

• Hand-tuned per-lane colors along a cyan → blue → purple → magenta gradient that matches the logo.
• Glowing tube borders, soft outer halos, and scanline textures only inside the active press zone so the tappable area is instantly readable on hold tiles.
• Ambient floating tiles drift continuously down behind both the start screen and the game-over screen.
• Animated "neon tile" START button that physically slides down the board into the game on press — no jarring screen transitions. Same treatment on the PLAY AGAIN button.
• Score-burst flash animation on every successful hit.

🧠 Smart Lane Distribution

• Lanes are picked dynamically rather than randomly: the algorithm avoids consecutive same-lane spawns and balances left vs. right side usage.

🎯 Forgiving Hold Timing

• Hold tiles only require 75% of the full duration — releasing slightly early still counts.
• The hold-progress fill uses a soft gradient fade at its top edge instead of a hard line, so there's no visible pass/fail boundary to fixate on.

🎼 Scoring

• 10 points per beat cleared (so a 2-beat hold = 20).
• High score saved locally and shown on the start and game-over screens.

📱 Mobile-First Input

• Multi-touch support — different fingers on different lanes are tracked independently.
• Coordinate-based hit testing rather than lane-only, so taps register exactly where your finger lands.
• touch-action: none and user-scalable=no to prevent scrolling/zooming during play.
• Viewport sized in vw units (9:16 portrait) so it scales perfectly across phone screens.
• Mouse-up listener attached to window so releases register even if the cursor leaves the canvas.

🛠️ Tech Stack

• Pure HTML / CSS / JavaScript — zero dependencies, zero build step.
• HTML5 Canvas for the 360×640 game board with hand-rolled rounded-rectangle drawing and gradient fills.
• Web Audio API with OscillatorNode square-wave synthesis —