This is pretty great!
Trackball control is basically like a joystick or keyboard: x-axis jumps a letter. (# - A - B - C - etc) y-axis cycles through individual games.
Spinner control is treated like the x-axis, so turning the dial jumps letters. That seems like unexpected behavior though... If there was an option to set the spinner to use the y-axis, this would be perfect. A sensitivity adjustment would be nice too, but I'm thrilled this exists at all.