Nam Dinh Chess (John, February 2013)
In issue 61 of Variant Chess (page 107), I described a game played in the Vietnamese city of Nam Dinh, which I called Nam Dinh Chess because the name Vietnamese Chess had been used for something else. This game offered an elegant final phase which I expounded in the next issue (pages 121-122), and I was therefore very distressed to receive a report from Mats Winther that it appeared to be totally unplayable because White had a forced mate in two from the game array (Variant Chess 63, page 162).
To my delight, I have now been told by Mats, following experimentation by Robert Reid, that the game can be made playable by a very simple change to the rules which I gave in Variant Chess 61: all that is needed is to replace "Men ... may not capture" by "Men ... may not capture a king" (emphasis added). He has posted a description of the game thus modified on the web (see http://hem.passagen.se/melki9/nam_dinh.htm).
Mats tells me that in this form the game is a good one. "We have set Zillions [a computer game-playing system, see www.zillionsofgames.com] to play against itself. There is a win in most games, sometimes before 50 moves. The first party seems to have a considerable advantage, which is very good. If there is a pronounced first-move advantage, which is difficult to neutralize, then white has a problem, namely how to achieve a win; and black has a problem, namely how to achieve a draw. This is ideal. This is why Western chess is such a good game. It also means that if the white player loses the initiative, then it goes to black, who has a big chance of winning. This is why hunt games function so finely: the party with the many pieces is always winning. In games with few pieces, played on a small board, this is necessary, I would say. Otherwise it's too easy to neutralize the opponent and the game becomes boring" (e-mail from Mats to myself, 4 February 2013, slightly edited for publication). We normally try to design games so that the players have equal chances, but this way of achieving it, by making White's chances of winning and Black's of holding him off approximately equal, is new to me. On reflection, it is an entirely reasonable one.
Having seen the simplicity of Robert's change to the rules, I wondered whether I had made an oversight when translating them for Variant Chess 61. I no longer have convenient access to the book by Miloš Zapletal which appears to be the ultimate Western source for the game (David Pritchard's copy, which I used when preparing the material for Variant Chess, went to the Musée Suisse du Jeu in June 2012 with the rest of his Encyclopedia material), but Robert tells me that he obtained the rules from a Czech web site "Klub přátel deskových her" (the precise page being www.deskovehry.info/pravidla/viet-sachy.htm), which cites Zapletal's book as its source, and we agree that the rules there are exactly as I gave them in VC. So for once I can plead "Not Guilty", and it would seem that the error lay further back.
Be all this as it may, it is pleasant to see that the game has been rescued. The endgame analysis which I gave in Variant Chess 62 is still valid under the new rules, and Robert comments: "This kind of endgame with a king and several pawns against a lone king is in effect a hunt game, and a unique one too, since only one of the hunting pieces is capable of capturing the quarry."