PuZzLLe

On every level you have to put puzzles from a predetermined start point so that they correspond to the final result. But the size of a space for the puzzles is too small so you have to try your best to pass the levels. The first few levels are not so hard, but as you pass the levels, the difficulty increases. All in all, it is a rather good brain practice.
As you progress, you'll have to try all sorts of theories in order to find out the solution to the level.