This app was mentioned in 4 comments, with an average of 2.00 upvotes
If you're looking for a simple puzzle game I highly recommend Kerflux. Its a game of sliding different waves so that they combine to make the wave on top. As you will get closer to solving the puzzle the music will get louder. It's super simple and easy to pick up. As a bonus it has beautiful minimalistic graphics, a great soundtrack, and no ads.
Kerflux is a great time waster if you're into that sort of game. They do ask you if you'd like to pay for the game a little while in, but you don't need to, and it stays ad free.
Is it Kerflux?