Developing the music systems for Chime was an interesting assignment.

In the early versions of the game the music system was based around a simple drum beat, and everything the player does adds musical components. The gameplay rules worked differently and the player had almost total freedom to build music.

Timing was controlled by horizontal position of shapes and pitch by vertical position much as it is now. This was great, but it lacked musical structure and variation, and would have been impossible to incorporate pre-existing music into a level. We always knew that having a range of interesting music was going to be crucial to the game’s character and success, and the system needed to allow almost any song structure.

Backing track
The first thing to tackle was the backing track. We experimented with adding musical layers (instruments) over time, but decided to go for separate sections, eg intros, verses, choruses etc as this allows for greater flexibility, and the effect of adding layers can still be created.

Melody/Harmony
The nature of the CHIME gameplay means that the player could be placing shapes anywhere on the grid, so we need a system that always sounds good, whatever random thing the player ends up doing. This is easier said than done!

If you have a song in a specific musical key (say Cmajor), it doesn’t mean that all notes from that scale sound good with all sections of that song. There are always notes in the key that clash against certain chords. Also many songs don’t stay in the same key anyway, and some drift through many keys constantly (eg jazz)! To make matters worse often the strongest notes for one chord are horrible against the next chord. So it’s a shame to lose something musically strong in order to prevent something that is musically bad.

The solution was to define a set of “legal” notes for each chord in the backing music (usually a scale of 5 or 6 notes). This means that the notes change on the fly for certain chords in order to stay “legal”. The result works very nicely. We then took it a step further. If we can use this system to avoid musically bad combinations, we can also use it to emphasise the most musically interesting combinations. Suddenly very interesting, often strange … and sometimes downright beautiful melodies started occurring. A great result.

The final system should gracefully accommodate key changes, unusual chord progressions, and jazz harmony. Pretty much anything you can build with western music!

Rhythm
Each column on the game grid represents a division of musical timing. The number of columns is defined on a per-level basis, allowing almost any conventional and experimental musical timing. For sensible game play reasons, the width of the grid cannot change size mid level, meaning that all sections of the song must be the same length.

In Practice
Brazil by Philip Glass proved interesting. It was the first song that was delivered, and it really put the new music system through it’s paces! Quite literally testing every part of it … It has interesting chord changes, a constantly fluctuating tempo, and an unusual musical structure based on changing meters of 5/8 and 6/8. Amazingly the system held up well … mostly!

A couple of sections of the song changed pattern and the music loops no longer matched the width of the grid. As we had no other solution I had to chop up those bits, so they would conform to the width of the grid. Obviously I took extra care to remain true to the spirit of the original, and I hope that no-one but Glass himself and his most studious disciples will ever notice the differences!

Joe Hogan – Lead Audio Engineer