I am 8 years old and I got Crazy Machines for my Birthday. This is the best game in the world but if you don't like complicated things you won't this game. The four main things are fire, rope, electronics,and the next one I will let you discover. You can either build your own machine or you can figure out problems that may seem hard but after you've done them awhile they are easy. Some of the things that you can build with are boards, balls, robots, cannons, goo, blimps, cords, gravity controlers, scissors, tubes, and plants. Buy this game and have tons of fun!