World of Goo is a physics based puzzle / construction game. The millions of Goo Balls who live in the beautiful World of Goo don't know that they are in a game, or that they are extremely delicious.
With games as popular as World of Goo, it's hard to add anything new to what was written over and over again.
If you haven't heard about it yet, you live under a rock and should try it.
One of the most refreshing new titles in the past years that proves indie ingeniutiy beats wads of cash in quality any time.