Ok here's the basic idea. have you seen compicstrips with a complex machine that does basic objectives like waking a person up and prepare breakfast? Using simple things like levers, birds, balloons, rope, all letter labeled so you could read what each step does.
In the game, you will be given an objective and you have to accomplish it using given things at your disposal such as seesaws, ropes, pulleys, balloons, balls, etc. for example, your objective is to pop a balloon, that is tied to a rope that went through a pulley, which was tied to a seesaw, or something like that, and you are given a pair of scissors, some pipe, and a spring with a wooden plank. there's a ball hanging at the other end of the screen. you have to put the scissors by the rope to cut it, but you need something to make the scissor snip. remember the ball? you have to use the pipe and the spring to make the ball go to the scissors to make it snip so the balloon lifts up and hit the pin right on top of it.
Simple? Yes. but when you reach the expert level, you will fry your brains out and you'll be needing a HSF on your head.
It was a classic, and there's already a re-release of the game. And the good news to those who liked the game, there's a new one called The Incredible Machine: Even More Contraptions. I have this one and I still can't finish the Expert level. I have spent sleepless nights just to solve one puzzle. All you need is some basic knowledge of physics, common sense, a little imagination and creativity, and a lot of patience. The graphics ain't that impressive but they have used some 3d graphics, compared to the first two versions, which was entirely 2d.
I suggest if you want to rest your eyes from playing too much FPS games, and want to use your head for once, this game is for you.