Tap or click the center to start or stop. Tap the left edge to decrease the tempo by one, or the right edge to increase it by one. Hold either edge to keep adjusting. Swipe up in the center to increase the tempo, or down to decrease it. Swipe slowly for fine adjustments, quickly for bigger changes. Tempo ranges from 20 to 300 beats per minute. You can also use Space or Enter to start or stop, and the up and down arrow keys to adjust the tempo.