The game becomes impossible after lvl 120-130 for free to play players. In a day, you can earn ~ 50 gems, but all good planes are 5k gems. But then, you need to merge two planes in order to make tier 2 plane which costs 2k gem. Then same for tier 3. Gems are really expensive to buy. They never give any free stuff. It doesn’t matter if you watch all ads, you cannot keep up with a paying player. I mean u cannot even reach them if you play this game for 10 years by doing all quests, watching all ads. Such a good game to play, with such a horrible management and strategy. I do not recommend this game to everyone.