What's the maximum number of moves a game can go on without one of the players being able to force the 50-move draw rule or a draw by repetition? The longest game on this site going on now is 166 moves.

How long is a piece of string?

it is the same kind of question as the possibilities are endless if you set out to try this eg. 1a3,Nc6 2 Nf3 and then move knights around for 49 moves before another pawn is moved once. then the sequence continues.

For real, ive seen 188 moves and drawn on insuficient material.

I believe the longest possible game is 5, 500 moves long. Not that this would ever happen unless both players were trying... 

About 6,300 if I'm figuring correctly. Every pawn would have to promote and every piece be captured only when necessary to continue the game.

Edit: 16 pawns * 6 moves each + 30 capturable pieces - 8 captures that would have to be made by pawns comes out to 5,900. A couple moves will also be lost when pawn moves and captures have to be switched back and forth between white and black but I don't really feel like figuring the rest of that out.

http://blog.chess.com/kurtgodden/the-longest-possible-chess-game

Cheers TadDude, that's exactly what I wanted to know - thanks for the link.

Till its over by time or someone checkmates their opponent.

Gee and I thought my 90-move draw was a long game!

 No you're wrong.

Rich, I wrote that on 17th Dec 2008 at which point I was 100% correct. Now (Fri 20th March, 22:45 GMT) the longest game going on this site is 152 moves. The trick is to look at the date and time of the post at the top left hand side of the post.