Simply put, if you don't buy this game then God will kill a kitten... and a puppy!
Whoever played the first Portal knew that it was a great concept. A short, but very funny and well made game. This is the game Portal deserves to be. The graphics are great, the gameplay is very different but sooo rewarding and the writing... oh the writing is just spot on in every way.
So to reiterate, do you want cute little animals to die? Hope not.