Hayden Bursk, aka CDMer ohtravioso, has built a brilliant free game-slash-step sequencer for Windows, downloadable free. The ghosts represent music tracks moving across a grid; drag and drop bubbles representing sprites in one of four different views for different samples and simultaneous tracks (4 ghosts each = 4 tracks x 4 screens = 16 tracks).
Beat Step Sequencer [YoYo Games]
You can make your own games at YoYo using simple tools
Where it gets interesting is the ability to change the direction of the moving ghosts. Hold down the W, A, S, and D keys and click on a square, and you can add an arrow that redirects the path of the ghost. That allows you to create irregular, syncopated patterns and manipulate a pattern as it unfolds rather than let it repeat endlessly.
Part of why I think a lot of electronic music ends up being needlessly repetitive is that the interfaces we use too often encourage that repetition — or make it too difficult to introduce change. You can work around that limitation to inject variety, or even musically harness the repetition itself. But changing just a key variable in this case makes a very different step sequencer.
The step sequencer also works with your own samples, so you could actually use it live. Now if it could just sync … get that tap tempo ready.
Next step, Hayden: add in Pac-Man himself (or Ms. Pac-Man, if you prefer) and let us play the game while playing the samples!