LVL 2D/3D Puzzle App
There are plenty of awesome puzzle apps that can give your brain a workout and help you kill some time on your iPhone. LVL is a minimalist puzzle app that involves solving puzzles in 2D while thinking in 3D. You will have to think of replacing pieces on its faces to solve puzzles.
The game has over 50 levels and 150+ puzzles. You can spend hours solving all its puzzles. The game blends 3D and 2D views to give you a challenge. You can try the app for $1.99.