The last 10-15 levels having to place wood planks to stand on was kind of redundant, and an artificial way to increase difficulty, but in terms of quality for a free game, it’s there.
My biggest complaint is the anticlimactic ending. Once you beat mission 40 it just acts like it never happened, so essentially the end-game is repeating the same exact hardest level over and over again. So, 0 replay ability. I suppose that’s to be expected from a freemium, but it’s too bad they didn’t innovate a little further beyond 40 stages and make an ending that was at least satisfying.