Lots of fun
The basic premise is the same at every level: a little dude is traveling in time with his smart-aleck backpack and needs to build vehicles out of odds and ends. Despite the simple structure, it is very enjoyable and the physics of the game are very impressive - small changes really make a difference in the way vehicles perform. The scenes and challenges are good. The ability to re-do puzzles using a time-traveling feature (very easy to use) is great.