15 mins, 3 puzzles and got 5 ads, too excessive. If the ads didn't out number the puzzles it may of been something to use to relax. There are better ways to monetize a free to play mobile game to get more users and make more money. Example would be give an attempt system and if you run out of attempts refresh by watch an ad. Could also offer an ad to retry before a cooldown timer or watch an ad to gain an extra vial if needed. You can also add customization to customize the look of the vials.