Crucial Pain is a simple but addictive puzzle game created by the digital agency Out of Scope Dev. They released it both on the web and on iTunes, and even made the source code available on GitHub, so you can learn from it or create your own levels.
In the game you use physics to fling the puck around, trying to get to the exit. Various things block your way and contact with walls removes one of your 3 lives. The levels get more tricky as you progress, but all have the same smart wobbly line-art style visuals.