Rhythm action is a type of game where the player pushes a button (or other simple sensor) in time to music or other on-screen cue. Almost all music games are rhythm action games except the karaoke genre, such a SingStar and Karaoke Revolution.

Types of Rhythm Action Games

Dance

Dance Dance Revolution.

Instrument

Donkey Konga, Drummania, Guitar Hero, Rock Band.

Misc

Parrappa the Rapper.

Programming Rhythm Action Games

Creating Music Files

Analog music boxes have a series of notes they can play.

In this case, it would be four.

[note 1]
[note 2]
[note 3]
[note 4]

They also have a metal disc that has raised bumps which hit the notes as it spins.

If we take this concept and apply it to the "notes" of a Guitar Hero / Rock Band game.

// every segment represents 1/25th of a second. 
// an x represents a "note"

          1   2   3   4    5   6   7   8    9   10  11  12   13  14  15  16 
[note 1]| x |   |   |   ||   |   |   |   ||   |   |   |   ||   |   |   |   ||
[note 2]|   |   |   |   || x |   |   |   ||   |   |   |   ||   |   |   |   ||
[note 3]|   |   |   |   ||   |   |   |   || x |   |   |   ||   |   |   |   ||
[note 4]|   |   |   |   ||   |   |   |   ||   |   |   |   || x |   |   |   ||

The above would hit one note a second, each one a different note.

This could be stored as a 2d array.

As the graph above is 4x16, it can be stored as :

array(1,1) = "x"
array(2,5) = "x"
array(3,9) = "x"
array(4,13) = "x"

Extended Notes

Playing Music Files

Music files could then be played by this method :

a timer goes off every 1/25th of a second
the timer resets itself
and increments a counter
then checks the array (using the counter) to see if any targets are to be created

Syncing Visual Targets with Music