You can play Glowsynth by pressing the keys on your keyboard (e.g. A, W, S, E form the start of the chromatic scale), you can click your mouse, or you can even hook up a MIDI controller.
Glowsynth is a fork of Nik's Pen Sparks, which in turn was inspired by some of Seb Lee-Delisle's particle experiments and old Flash tutorials. Nik designed and coded the particle effects, and I hooked up the audio and midi functionality. Thanks, Nik!
Find out more at http://outputchannel.com