Switchyard Sonata

Switchyard Sonata is a routing puzzle that becomes a rhythm game.

Genre collision: routing puzzle × rhythm performance

1. Compose. Three passenger shapes want three stations: △ Glass, ○ Brass, ◇ Velvet. You write a repeating switch score. Rows are switches A, B and C, columns are beats in a 4 or 8 beat loop, and each tile points up or down. A train reads each switch on the beat it gets there, so one tile can reroute several passengers.
2. Perform. Once every route works, the trains run and each arrival becomes a note. Tap on the beat as arrivals cross the strike line. Trains that arrive together form a chord and need one tap.

The two genres depend on each other. The lower A to C branch takes an extra beat, so your route decides when each note lands, not just where. The puzzle writes the song you then have to play.

Six movements

1. First light: one switch, a city waking up
2. After hours: take the longer line to Velvet
3. Crossing paths: two ways to Brass, find your own
4. Night market: eight beats, a brighter bustle
5. Blue hour: leave room for the quiet notes
6. Last train home: bring every voice home, together

Controls

• Mouse or touch: click a passenger to trace its route, click tiles to flip switches
• Keyboard only: Tab to any control, Enter to use it, arrow keys to move between score tiles
• Space (or the round button): tap arrivals during a performance
• Escape: pause · M: mute
• Preview routes plays your score without timing. "A little nudge" makes one useful change and keeps any valid solution you are building toward.

Accessibility and relaxed play

• Relaxed listening: solve the routes, then hear arrivals play themselves. No timing score, and it still unlocks the next movement.
• 80% tempo option, reduced motion setting, mute
• Shapes, not just colors, identify every passenger and station. Visual cues are enough to play with the sound off.
• Finishing any performance unlocks the next movement. You don't need a perfect score.
• Progress stays in your browser. No account, ads, tracking or network calls.

Credits

Made by Touko Ursin for Bezi Mega Jam (Genre Collision). The art is original Canvas geometry. All sound is synthesized live in the browser with Web Audio oscillators; there are no samples or recordings. No third-party assets, libraries or fonts beyond system fonts. MIT licensed.

AI assistance disclosure: OpenAI Codex and Anthropic Claude assisted development: design, code, procedural visuals, sound synthesis code, tests and docs. All sound is synthesized locally at runtime; no AI-generated audio or images ship in the game.

Tip: play in fullscreen with sound on. Headphones help with timing.