I uninstalled this game. You can earn coins to buy collections of puzzles or to buy singke puzzles. This game by far is the most expensive!!! A single puzzle here costs 1000 coins, in my other games they are 20 to 50 coins. A collection of puzzles here cost 4000 coins, in my other games they run about 400 coins and you get 18 to 20 puzzles which you get to see before you buy them...not here, you only get to see 1 puzzle before you buy...and you get ads in the middle of a puzzle...that's greedy!