Hi yes actually Ketchapp did something similar now. they even have a fidget spinner game. I know what you mean for now I did it as an app but might create a game later on or add a game mode inside the app like a challenge kind of thing. Yes Actually I spent money on Chartboost ads around 200 dollars and the rest happened organically. It is about the right timing and pure luck to tell the truth. I am not sure If I published it now, it could get the same amount of installs. It was just right time for the term fidget spinner when the market wasn't saturated.So in a way we can say it was ASO in keyword wise. It might also be the screenshots don't know.