Available for iPhone and iPad, TinkerBox is a free-to-play physics puzzle game.
"While it is full of interesting science facts and teaches basic engineering concepts, TinkerBox is more than just educational!
Take the tools in your hands to explore your creativity and imagination with Invent mode. Build outrageous machines, share them with your friends, or download popular inventions from online.
Stretch your brain through the devious Puzzle mode. Get immersed in physics-based puzzles and mechanical concepts, where your only hope for success is your creative problem solving."