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.
Haha yes tell me about it! It is pure luck to tell the truth I just gave it a chance and it worked this time.