Touch: Tap "Show touchscreen voicing buttons" to show the chord voicing buttons (landscape orientation recommended). Tap on notes on the circle of fifths to play and select a bass for the voicings.
Mouse & keyboard: Hover the mouse over the pads to select a bass note. Use the keyboard to play chord voicings on the current bass. Press z to play just the current bass note; you can hold/release it independently of the voicing buttons.
Keyboard mapping for voicings:
Let the Autocomposer generate for you an infinite stream of bossa nova!
Tip: Try clicking keys close to the ones you last clicked (or close to the last-queued bar's key). However, the Autocomposer can handle moving from any key to any other key; feel free to play around!