The game is very fun, with good reliability. However, you need gems to advance and the game provides very few for achievements. To upgrade one item you need ten gems, but you only get maybe one gem a day and seven for leveling. To buy gems is outrageously expensive, like $2.39 for 12 and again you usually need ten for an upgrade. The ads also don't let you exit after they finish, and then when you exit the game you dont get your reward for watching, so very scammy.