If you tap the bass section and the chord section at the same horizontal line very relaxed sounding chords are played.
Tapping bass and chord section at distant vertical positions results in a more tense sound.
You can also create tension if you play relaxed Chords and then play other chord and bass combinations that are vertically far away. The first chord you start with be perceived as an anchor and everyting far away from it will create tension. The tension is resolved when going back to the anchor position.
To create a sad musical piece you can stick to the the darker horizontal rows of the chord section (minor). To play a happy one, use the brighter rows (major).
But you don't necessarily have to only play bright rows to play a happy sounding cadence. Instead you can weave minor chords into it. The mood of the cadence is determined by the last chord you play.
The video below demonstrates this in more detail.
A cadence is a well sounding chord sequence. To play a (happy sounding) major cadence, tap or swish horizontally over the bright rows in the order shown below.
To play a (sad sounding) minor cadence, tap or swipe horizontally over the darker rows.