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.
This has become one of my favourite games to play when I have a bit of spare time but not enough to invest in something more indepth.
I only wish I had an iPad to experience it that way; the idea of being able to move the goo balls with my finger sounds amazing.
10/10 that is well deserved!