I really like this one! the style is great. i did find that the difficulty curve is a bit odd. i personally found most of the rounds very easy, but the last one impossible. but i think it should be difficult to beat the devil!
i found the last one easy, but the other rounds after round 1 harder. For me, what helped with the final round was knowing which cups to ignore, and seeing the "shape" of the 3 balls. Either that, or I just leaned on items.
