Mosaico: the new tangram comes from Hideki Matsui. This game came out 2 years ago, and I missed it. The object is to fill the grid with rectangles completely.
How to make a rectangle: find two numbers that are the same and tap on them. Those will become the opposite corners of the new rectangle. Unless of course the width of the rectangle is 1. It still works.
The game does have 8 levels of difficulty. Your task is to earn stars (based on time) to get to the next level. But you can of course keep going forever on any level that's already been conquered.
I played this game the past 4 days and got to level 5.
Good game and difficult.