Remember hat with the apple and then open it. Difficulty of the game is increased as per the levels.

As the level increases number of head and speed of shuffling increases.
1 – 3 levels – 3 hats.
4 – 6 levels – 4 hats.
7 – 9 levels – 5 hats.
10 – 12 levels – 6 hats.
13 – all next levels – 7 hats.

You have to be very sharp and fast to keep the track.