Press on the green and drag away from where you want the ball to go; the arrow shows the direction, and the longer it grows the harder you hit. Ease your finger back toward the starting point to lower the power. Let go to shoot, or return to the marked circle to cancel. Keyboard: arrows aim and set power, Space shoots, Escape cancels.
Water and out of bounds: one stroke, ball returns to where the shot started. A hole ends at par + 4 (capped).