This is the equivalent of a platinum trophy although you only get credit for a gold. It will unlock as soon as you have completed all other trophies. The most difficult trophy to unlock is the snap + slide 15 piece puzzle. I have posted a detailed guide to assist you. The guide will also apply to the easier snap + slide puzzles.
The second most difficult trophy is the digit chase prize. I have posted guides for the three stages as well as the cumulative trophy. Do not be discouraged by early times. You will very quickly advance on the learning curve.