Disgraceful practice by the game developers. They deliberately make it easy and addictive early on and it's a very nice game to play UNTIL you get to about level 145 and it's impossible to get further without paying for coins and special moves. They are not happy with the advert revenue or by offering a one off payment, they want you to pay again and again. I don't mind paying a one off fee for a game or to remove ads, I've done that many times. But I object to the constant begging for money.