Had a great game, but InApp purchases make it unplayable

This app presents as the full version of a usual tower defense game Run through. Would also be a great game, but unfortunately not you get to the beginning, that the most important "experience points (Stars)" and additional M-Taler just very hard to get. These are typically either through InApp purchases, by inviting its Facebook friends to the game or the level finishes very well. These stars are then but Essential to his units to upgrade, to give them better weapons and defense. Quick one has then been used up and comes to 15 - LVL 20 (which is not even 10% of the available levels are) not, unless one star and similar buys it.