Finding a game that is both engaging AND completely free is a rarity. Theres endless puzzles of various difficulties so theres always a challenge waiting for you! However, my only complaint is that when the ads play (a necessary evil Im totally fine with) it adds to the timer on the game. So if Im watching an ad for 20 seconds, before Ive even started the puzzle, the timer is already at 22 seconds. As far as problems go, thats nothing. Its just a tiny bit irritating