Mouse, trackpad, finger or pen: which should you use?
Whichever you use most, and the same one each time. The result belongs to your hand and the tool together: pushing a mouse across a desk and drawing with a fingertip or a stylus are different movements, and neither is simply better. To see whether you are improving, compare runs made the same way.
How are the drawings scored?
Against the ideal shape. For Perfect Circle, the circle closest to your line is worked out, and the less your line wanders from it, the higher your roundness percentage. Straight Line works the same way with the closest straight line.
The Shape Tracing Game measures two things instead: how much of your line stays inside the band, and how much of the band your line covers. Your score is the two multiplied, so tracing half the shape perfectly scores about the same as racing round all of it with half your line outside the band.