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I ask about the exact rules for the chess variant known as pawn wars. The starting position contains only pawns which move exactly like in chess and the first to promote wins.

[FEN "8/pppppppp/8/8/8/8/PPPPPPPP/8 w - - 0 1"]
[Title "The first to promote wins"]

But it should also be stated how to evaluate the end result when the side to move has no legal moves left. Is it lost or stalemated? I have been thinking about this game for years as a study tool for beginners but also as a philosophical research project into the game of chess for advanced players. I have found it recommended on several websites by kid educators.

I would like to write an engine to play this game but I cannot make up my mind on the best statement of the rules to maximize its practical relationship to chess. Are there any guidelines by experienced educators or existing environments to play this game? Any ideas how and why to fix the rules?

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  • Can you expand on the situations that you find problematic and the different rules you are considering?
    – hkBst
    Commented May 27, 2016 at 7:22
  • A blocked position should be drawn or won by the side which has made the last move? We could go for a zugzwang game or for a stalemate game so to speak.
    – MichalRyszardWojcik
    Commented May 27, 2016 at 7:24
  • When we go for stalemate in a blocked position then what to do when one side has a passed pawn on its way to promotion while the weaker side has run out of moves (blocked pawns or no pawns left). Is it still a draw?
    – MichalRyszardWojcik
    Commented May 27, 2016 at 7:26
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    I do not think it matters a whole lot, but off the top of my head I think I prefer not being able to make a move to be an instant loss.
    – hkBst
    Commented May 27, 2016 at 7:31
  • My previous comment is specifically about the situation when both players have no more moves. When only one player has no more moves then that should definitely be a loss for that player.
    – hkBst
    Commented May 27, 2016 at 7:36

3 Answers 3

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A situation like this, with Black to move, is a win for White:

[FEN "8/8/8/3pP3/3P4/8/8/8 w - - 0 1"]

Why? Well consider the case where White has been skillful enough to take all of Black's pawns and promotes easily. By definition, Black has no legal moves. From a training game we do not want to teach that losing all material leads to a forced draw. That would be a poor lesson to learn for building a knowledge of King and Pawn endings on.

A note on passing. It seems that to implement this in a program, a player with no legal moves is forced to 'pass', just in case a situation arises that allows the 'stalemated' side to have a legal move later on.

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The common version of the rules for pawns-only chess (or pawn wars) states that the stalemated player loses, see https://www.chessvariants.com/diffsetup.dir/pawnsonly.html and Is the result in mini-chess known with perfect play?. In the latter thread you can also find the outcome of the game with perfect play in case you are interested.

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First you need to prove that someone can force a promotion. That is far from obvious.

Then you would need to prove that it is not , with best play, always a blocked position with the same player making the last move.

I suspect that this is just a puzzle that could be solved by computer that shows there is one best outcome that is always the same.

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