The shortest number of moves that a game of chess can have is 2, as far as I know:
- White moves pawn from
f2
tof3
, black moves pawn frome7
toe5
- White moves pawn from
g2
tog4
, black moves queen fromd8
toh4
. Checkmate.
Which results in this situation:
There might be more games which end after 2 rounds, but as far as I know there is no game with fewer rounds / moves.
How many moves do the longest games take?
I thought I have read that the number is about 8000 moves.
A finite maximum number exists, because of the fifty-move rule and threefold repetition and I assume that players claim draw by those rules if possible.
Please link also to the source of your information!
edit: Jacob Schlather mentioned a blogpost with this information
[...] The Belgrade Marathon was a contest between Ivan Nicolic and Goran Arsovic that lasted over 20 hours and ended in a draw after 269 moves due to the so-called “50 Move Rule”, [...]
Source: The Longest Possible Chess Game
So the longest game that was actually played took at least 269 moves. Later he explains how he comes to 5,870 possible chess moves.