Seeing Prof. Nash enjoying his walks on campus is one of my fondest memories from grad school. This is very sad.
I was curious to learn more about his work a while ago and had looked up his PhD thesis. Here's a link: http://www.princeton.edu/mudd/news/faq/topics/Non-Cooperativ....
What struck me was that it only had 2 references to prior work! That's how you know you're doing innovative research.