Game becomes increasingly harder to the point you cannot pass a level without having to purchase coins. Game cleverly will not let you pass a level unless you use coins. Eventually you'll use up the coins you've collected and the only way to move on is to purchase more. Also I noticed that it seems when you free bombs etc for a given period of time the game runs very slow limiting the number of attempts to pass levels. Game is very well written to empty your bank account. FYI POINT.