Another addition to the room escape realm is Escape If You Can. There are several different apps that I prefer in this genre and this would be one of them. The reason that Escape If You Can is great would have to be because of the complexity of the puzzles.
There are multiple sections within each room that will have you scratching your head and trying to connect the dots. Critical thinking and an outside-the-box attitude is all you need to enjoy hours of free entertainment.