You know, 99% developers make games to gain revenue? Well its a fact. I'm so pleased this developer made this game for the players. I haven't found any ads in the game and I also didn't see any in app purchases although I didn't search for them. This game made me feel really good and relaxed. The music is very appeasing in zen mode which is what I play 99% of the time. In zen mode you cannot lose, you just enjoy the amazing music and the amazing graphics! Wow! Well done developers!