Update: dropping two stars because some ads crash the game! I get the need for ads, you need to keep the lights on somehow. That's fine, but when your served ads for a particular gamw that forces you to play it for an indeterminate amount of time before you figure out how to get back to the game you want to play, that's a bridge too far. Still a very good version of Sudoku, just be more mindful of what ads you serve.