I was playing around with famitracker and I was seeing how different chords sounded, and something I noticed was certain notes gave a chorus effect when played with itself an octave higher. I think this is unintentional, because older systems had to round notes off to the nearest available frequencies, but it does give a desirable effect.
What games take advantage of having slightly out of tune octaves? Was this ever done intentionally?
Crystalis and
Startropics intentionally detune unisons in their soundtracks. Those are the two that immediately come to mind, but I'm sure this effect is used in a lot of games.
The same principle is used for the
chorus guitar effect pedal, or
doubled vocal recordings, or why a string orchestra sounds different than a string quartet, etc.
I meant games that used a single note scale, but deliberatly detuned octaves.
You can detune any perfect interval for a chorus effect, it's just strongest with the unison, and second strongest with an octave.
Since you asked for detuned octaves specifically, I heard some in
Pictionary today. The whole soundtrack is full of detuned effects like this. Follin more frequently uses detuned unisons than detuned octaves (the effect of the detune is stronger this way), but also might use different duty, echo/delay, or other combinations; there's a lot of different tones you can get out of various ways of doubling with a second voice.
The pitch is usually given as an integer number written to a hardware register, resulting in approximative tune. Thus all music tuning in games is pretty much approximative.
In NES' case, when notes go higher, less bits are available and the pitch precision becomes lower, resulting in more "wrong" notes. SNES is the opposite, but since it has more bits (14 bits vs 11 for NES) it's hardly noticeable anywhere.