Games Of Chess

There are more possible games of chess than there are atoms in the universe.

Respected estimates of the number of possible board positions in
the first 40 moves of a Chess game range from 10^40 to 10^120. That's
from 1 followed by 40 zeroes to 1 followed by 120 zeroes:

http://mathworld.wolfram.com/Chess.html

To give a sense of how big the number 10^120 is, typical intelligent
estimates of the number of particles in the observable universe tend to
fall in the neighborhood of 10^80. So, if we take the number of
particles in the observable universe according to this estimate and
multiply it by 10,000,000,000,000,000,000,000,000,000,000,000,000,000
(!!!) we get a good approximation of the number of possible positions
in the first 40 moves of Chess, according to one widely-respected
estimate.