A free app for Android, by brennerd.

This logic puzzle will keep you thinking and keep your mind sharp. The game can be played for free and offline, so you can play it anywhere. The puzzles range from easy to very challenging. The app will give you hints when you get stuck, so you can use them to help you out. There is no time limit for the puzzles, so you can take as much time as you need to solve them.

The app provides an extensive range of different themes to keep you interested in the game. Each theme has a number of different levels, so you can get a lot of exercise and entertainment from the game.