In terms of chords and melody, Splatoon Main Theme has complexity on par with the typical song, having near-average scores in Chord Complexity, Melodic Complexity, Chord-Melody Tension and Chord Progression Novelty and below-average scores in Chord-Bass Melody.
Splatoon Main Theme is written in the key of A Minor. According to the Theorytab database, it is the most popular key among Minor keys and the 7th most popular among all keys. Minor keys, along with major keys, are a common choice for popular music. The three most important chords, built off the 1st, 4th and 5th scale degrees are all minor chords (A minor, D minor, and E minor). See the A Minor Cheat Sheet for popular chords, chord progressions, downloadable midi files and more!