A free app for Android, by Simply Entertaining.
The rules are very simple: you need to use your finger to draw a line to guide a ball toward the goal. The path you create will be drawn on the screen, and the level is completed when the ball reaches the goal. You will get hints if you can't figure out a puzzle. There are over 500 puzzles in the game, and the difficulty level is easy, medium, and hard.
The best part of the game is that the rules are very simple and that it is very easy to learn. The gameplay is very simple and fun, so even kids can play it.
It is a game that is great for increasing your thinking ability and enhancing your problem-solving skills.