One Touch Drawing isn't a drawing app. It's a game that makes you draw a continuous line to solve hundreds of challenging puzzles. It's a unique game that happens to be really fun to play if you like basic brain teasers.
One Touch Drawing asks you to trace a shape without repeating any lines. It lets you see the finished shape so you can think about each move before you make it. There's an easy "reload" button in case you mess up and hints show up if you've failed ten times, which is helpful; but these options are only available in the regular game mode -- not in the survival mode. To make up for that, the game's regular mode offers 300 different levels in three zones. That means there's plenty of fun to be had here, but the game will get tough if you're not very good at geometry. The puzzles get incredibly complex very quickly.
There aren't many games on Android that can compare to this one. One Touch Drawing is worth trying just for how different it is from other games. If you're ready for a new challenge, this one is definitely worth a shot.