Game, TwoDots, nice artwork and frustrating levels without in app purchaise

The makers of the hit game Dots are back with a brand new, addictive, free, puzzle game!
Join two brave dots as they traverse arctic tundras, navigate fiery jungles, and plunge the ocean depths. Sharpen your skills across 135 challenging levels while uncovering many exciting new features along the way.
https://itunes.apple.com/gb/app/twodots/id880178264?mt=8

pros: Nice minimal and flat design.
cons: Needed for expensive in app purchases.