bevy

  • 31st August 2026

Harmonicon: a rhythm game you play on a real harmonica

For once, something on this blog that isn’t C++.

Harmonicon is a rhythm game for blues harmonica. Notes scroll toward a hit line and you play on an actual harmonica, into your microphone, and the game listens.

The idea

The harmonica is cheap, fits in a pocket, and it hides everything: the reeds are inside, your tongue and throat do most of the work, and nothing about the instrument tells you whether the note that just came out is the note you meant. You can practise a bend wrong for a month quite happily.

Let the instrument be the input. Harmonicon captures the microphone, runs pitch detection on it in real time, and scores what you actually played against the chart. Every note you score is a note you genuinely hit.

Playing a song

The 2D play mode: a lane per harmonica hole, with notation and a tab readout above

The default view is one lane per hole: ten for a diatonic, twelve for a chromatic, taken from whatever the chart was written for. Blue notes are blows, orange are draws, and the number on each is the hole you need. Above the lanes there’s the phrase in standard notation and as harmonica tab, because those are the two ways harmonica players actually read music, and the panel on the right tells you which harp to pick up and which position you’re playing in.

There’s also a 3D view, which is the same game rendered around a harmonica model that moves with the beat.

The 3D play mode: notes travelling down toward an animated harmonica model

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