What's the greatest number of moves that could ever be achieved in a chess game?

The_Icestorm

more activity on this forum, prehaps?

MuhammadAreez10

The longest chess game has increased in number of moves due to the recent change in rules by the FIDE. It is 8848.

Deedlit

Actually, the correct number is 8849. 

From Ozzie's links, I found Sonny_E's analysis where he claimed the longest game as 5898.  His error is here:

"4. The responsibility switches a fourth time, so that black's king can miraculously mop up all of white's blundering pieces, except maybe for the last one, on black's 5898th, which would result in a draw by 50-move rule because black cannot cause checkmate or stalemate with only a king."

There is no need for this fourth switch if white already has no nonking pieces, or has the last nonking piece.

Tatzelwurm

Wrong.

Black couldn't capture all white pieces in the previous phase because white had still pawns to promote.

Elroch

A nice counterpoint to this discussion is this magnificent creation by Sam Lloyd: (probably) the shortest possible legal game ending in stalemate!!



Deedlit
Tatzelwurm wrote:

Wrong.

Black couldn't capture all white pieces in the previous phase because white had still pawns to promote.

No, there is no reason why white cannot promote 7 or 8 pawns during its first turn with control.  The opposing analyses all seem to suggest that the only way to promote all the pawns is to double up White's pawns on four files and double up Black's pawns on the other four, but there are many other ways to do it.

Example:  During Black's first turn with control, he moves his pawns to

a7 b6 c5 d4 e3 f4 g5 h6

During White's first turn with control, he promotes all of his pawns except for the e-pawn, by pushing them adjacent to the opposing black pawn and then capturing "inward". (axb7, bxc6, etc)

During Black's second turn with control, he promotes all eight of his pawns and captures all of White's remaining pieces except for the e-pawn.

During White's second turn with control, he promotes his e-pawn to a queen, and captures all of Black's remaining pieces. The game ends.

So three changes of control, and the game ends on whites 8849th move. (17697 plies)

Tatzelwurm

You are right. That's a good find.

Here's a sample position to illustrate the procedure:

The black pieces are already in the position where the white pawns will capture them.

We don't capture the last white piece but that saves us the 4th control switch and yields the extra half move.

So I agree with you that the longest possible game in chess ends after white's 8849th, or after 8848½ moves due to the 75 moves rule

Deedlit

Rule 9.6b.

https://www.fide.com/component/handbook/?id=171&view=article

coolsawesome6

HELLO?

1.a3 a6 2.Ra2 Ra7 3.Ra1 Ra8 4.Ra2 Ra7 5.Ra1 Ra8

 

Yes,who would do that,but this way the answer is:INFINATE!