These puzzles portray my interests: nature, gardening, crafts, home and storybook illustrations. I use this site with my phone and 140 pieces I find is the highest amount of puzzle pieces which is still usable with a smartphone and stylus. Any more pieces and the pieces get too small to grab and too messy to see properly. That's why all my puzzles are set to being approximately 140 pieces. Luckily you can play them with any number of pieces according to your preferences.