It's less invasive with ads than most mobile games. You can make steady progress using the in-game resources. It's presented as a game you progress through using skill, but you will be waiting around for ideal layouts if you can't force stages with power-ups or with paid continues. It's not good, but I'm usually killing time with it. So, that's something. I'm declining to include a star-rating as the windows I'd actually be willing to play this in exist outside of the time I put aside for games.