Basic principle

Acccelerando was developed from experiments on procedural generation of music based on physical effects such as gravity and collisions. Procedural generation means that the music is created automatically based on rules and formulas, changes constantly and influences itself. It is not composed or interpreted by a musician. You can decide for yourself how good Acccelerando is at this job; sadly, automatically generated music tends to become rather repetitive.

Still, it can be fun to play around with Acccelerando and try to build a scene that sounds interesting. And if you play an instrument yourself, you may want to try ad–libbing with such a scene as backing.


Instrument with two generated notes
Instrument with two generated notes

An Acccelerando scene consists of instruments that create notes. An instrument creates notes with

  • the desired sound (e.g. piano),
  • a certain pitch (C, D, E, F, G, A, B),
  • and a rhythm grid made up of sixteenth notes.

The color of an instrument is determined by the sound chosen. For example, pianos are red.

Instruments have two different play modes: sends notes and plays instantly.

Instruments set to send notes don't produce sounds by themselves! Instead, they produce flying notes according to their rhythm grid. As these notes fly around and collide (see below), they create tones.

An instrument set to play instantly plays its tone instantly according to the rhythm grid. This is particularly handy for giving the scene a backing track (bass or chords).


A "hot" note to the right
A "hot" note to the right

Instrument set to send notes send out note spheres according to their rhythm grids. These notes attract each other like planets in space, following Newton's laws: gravitation depends on mass and distance.

When different notes collide, they repel each other.

But when two notes from the same instrument collide, they merge to form a hot note.

At the next beat in the rhythm grid of the instrument that created it (e.g. the next quarter note), the hot note plays its tone with a pretty burst effect. The larger the note sphere, the louder the tone.

Tone played and bursted
Tone played and bursted


Using familiar touchscreen gestures, an Acccelerando scene can be panned with one finger or zoomed by spreading and pinching. A double tap centers the viewpoint to the full scene.

By tapping an instrument (tip: zoom in to hit them more easily), you can select it for editing or deleting. See the details under "Editing Instruments".

Demo video

This video shows instruments and flying notes in an Acccelerando scene.