One of the most beautiful video game soundtrack themes of all time, is the Final Fantasy VII Prelude Theme by Nobuo Uematsu.
Why is this theme so incredibly mesmerizing, uplifting and beautiful. Well, mainly because of the strong use of add9 chords, almost exclusively throughout the theme.
Why Maj (add 9) Chords = Beauty
To find out the reason for this, we first have to consider what interval the add 9 really is. So to create this “Beauty Chord” you start with a Major triad. Let’s take Bb Major: so Bb, D and F is your starting major triad.
Then you simply add the 9th interval, which is a C. And you have a Bb Major (add9) chord. However, in many cases this add 9 is played in close position voicing, making it an add 2 in practical terms. Now it is important for you to know that add 9 could basically be labeled as add 2 if you play it this way.
However, if you follow classic naming conventions of chords it should technically still be called an add 9 chord, simply because inversions of chords should not matter for the naming of the chord, but only the mark the bass note to show which inversion is played.
Anyway, regardless of how you choose to label this chord. It adds beauty and serenity simply because it is based on a major triad, that gives it that uplifting vibe, and has the added 2nd or 9th interval, which has that emotional tension that you can also hear in suspended chords. Making it a mix of a major chord and a suspended chords.
The final ingredient for that shimmering magical vibe that Final Fantasy VII Prelude uses, is to play the chord as a flowing arpeggio in several octaves. So experiment with playing styles as well when use use these Major (add 9) chords.