In this concept there are N different shapes, where N is the number of players. Each round one of each shape is laid out, and at the end of that round everyone must get one of them, and so every one must go to someone.

That's it. The shapes don't mean anything beyond that, and there's no reason to get one over another.

The trick is that everyone has some secret goal. Someone's trying to get 5 squares, someone else is trying to get 3 circles and 2 squares, etc. The first person, or people, to get above their goals win.

So, the game is just an arbitrary choice of "fine, I'll take the circle then so we can just get on with this turn", followed by the mistrust of "wait wait wait, didn't you get a circle last turn too?", answered by "well, yeah, but that's because no one wanted it last turn as well so I took it", "but why would you take something you didn't want two turns in a row? I'll take the circle", "Ok, fine, I'll take the square then", "Damnit. Someone else take the square and give him the triangle!"