In terms of chords and melody, Duality has complexity on par with the typical song, having near-average scores in Chord Complexity, Melodic Complexity, Chord-Melody Tension and Chord-Bass Melody and below-average scores in Chord Progression Novelty.
Duality is written in the key of F Dorian. According to the Theorytab database, it is the 6th most popular key among Dorian keys and the 35th most popular among all keys. The F Dorian scale is similar to the F Minor scale except that its 6th note is a half step higher (D). Chord progressions in Dorian have a characteristic sound due to the major quality of the chord built on the 4th scale degree. See the F Dorian Cheat Sheet for popular chords, chord progressions, downloadable midi files and more!