Hexaru

Drop tiles to the board and create same-colored blocks of five or more.

There are no fancy power-ups or quests or campaigns or hilarious achievements. It is just combining blocks while listening relaxing music.

And if you get bored, you might want to search for the eastereggs. :)

This game can be played completely offline.

Yes, there are ads, but whether you watch them is totally up to you. They help you out with your score and support the developers, but they are not needed for the game.