Sometimes the most simple things are the most perfect...
It is all about the fun - plain and simple.
It is about atmosphere, it is about art, it is about immersion. It is ultimately about people having fun making it, so that other people can have fun playing it. Painkiller reminds me of the good 'ol days when games were made to be played, not only to be sold.
Now...You go back to play Crysis. And I am going to replay Barracks - that masterpiece Painkiller level. Wanna bet who will have more fun?