The game relies on one simple mechanic: you draw something, and that line will repeat as it makes its way across the board. The aim is to get your line to touch the colored dots while avoiding the black ones. The idea sounds simple enough, but as you can see in the game trailer below, it can get difficult very quickly. You should prepare yourself for failure, a lot of failure.
However, the game is very well made, which helps a lot. It's well designed, with a solid soundtrack. Even better, the difficulty doesn't feel like a cheat, because the game isn't free-to-play. It will cost you $2.99 for the game, and there are no in-app purchases. It's definitely worth it, but you can always use your 15-minute return window if you're worried about dropping $3.