5 stars: Awesome game! Really well built, controls are great, puzzles are a nice level of challenge for a casual mobile game. My only suggestions would be improving the text associated with each unlockable picture so that it's more interesting or funny. Also, it would be nice to be able to specify what size puzzles you want to do next.
5 stars: Down to 4 boss puzzles to solve. Have enjoyed the game immensely, but do agree with other comments that the 3hr wait between boss puzzles is a tad long. Occasionally my changing from marker to X was missed but it wasn't a big deal. WOW. Came as a big surprise to discover I get to replay all levels (plus a few new ones) without the ability to place Xs; only markers. Just over 1/2 way through this challenge.
4 stars: This is a great game, should be 5 stars, but there's a couple tiny things that bug me, like, the 'random' puzzle selection loading the same puzzle 5 times, or the hints not actually working (though that seems to be fixed now). Again, awesome game, though, and you get what you put in.
3 stars: Game has an ad after just about every puzzle and time gates about 1/3 of the puzzles. It also asks you to rate it before starting ads which I think is disingenuous and deliberately deceptive. It's pretty minimal in features but are fine for the difficulty of the puzzles presented. Rare are puzzles that take more than 5 minutes. It's a fine puzzle app with a decent amout of puzzles. You're better off with something like Nonog...