This was a neat idea, but I found it difficult to control. It felt like I needed to circle the mouse around a lot to make changes, and I had to drag it pretty low along the bottom edge if I was doing a full circle. With only the top of the wheel showing I initially figured it would only be dragging it side to side a small amount, but that did almost nothing. If you need to spin the mouse around the wheel, then more of the wheel should probably be showing, to make it easier to get under for the circling. Even with dragging all the way around it felt like by the time I saw a rock there was not enough time to avoid it. There are probably tricks to control it better, but I did not find them. Maybe add some more details on how to move quickly enough to avoid rocks. I tried a few times, but was unable to get far.