Challenging and awesome. Only problem, for me personally, is I solved puzzle seven but it is not accepting my answer. Is it possible that there are multiple solutions? I understand the concept of making sure the tiles line up with the appropriate color, but for some reason it won't let me finish. I'm guessing that either there are multiple ways to win and you have it programmed for only one or I found a bug. Either way, I'm disappointed that I cannot finish the game since I love puzzle games. Hope this helps for any future installments.