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This item is a game information page
It belongs to categories: Orthodox chess, 
It was last modified on: 2005-04-22
 Author: Hans L. Bodlaender and Antoine  Fourrière. Marseillais Chess. Move twice per turn. (8x8, Cells: 64) (Recognized!)[All Comments] [Add Comment or Rating]
Greg Strong wrote on 2017-04-07 UTC

I expect 23 moves is probably in the neighborhood of what a well-played game of Marseillais should last.  Double moves lead to sharper tactics and bloodier games.  For example, defending a piece doesn't necessarily accomplish much, since the opponent can use his two moves to take the piece and then move the attacker away to a safe location (a kind of hit-and-run.)  Also consider that each move is really two moves, so this game had the equivalent of about 45 moves of conventional chess.

Unfortunately, if you run this test with ChessV it is going to crash.  There's a bug I discovered when trying to run this that I first had to track down and fix.  The version I recently posted was a "release candidate" to get it out into the wild so I could get people doing more testing and reporting problems.  So far about a dozen bugs have been found and fixed.  I hope to release an update shortly - possibly this weekend.  Then you'll be able to run similar tests.  The short explaination is that there was a bad interaction between the double-move and the code that handles en passant.

Why 12 hours?  Somewhat arbitrary.  The longer you let it think, the deeper it can think.  But the time required to reach the next level of depth increased exponentially, and the exponent can be quite high.  To reach enough extra depth to make a difference in skill might require a couple of days.

I should also point out that Marseillais is different enough from standard chess that we don't really know how to best program a computer to play it.  We are in uncharted waters here.  Almost certainly there are changes that need to be made to the standard chess algorithm for proper play of double-move variants, but we do not yet know what those changes are and it will take a lot of study and experimentation to find them.  If you're really interested in the details, chess programs have something called Quiescent Search that is very important, but this concept doesn't really work for double-move variants and it is not clear what should replace it.  You can read about quiescent search here.

But, all that said, this score is of what is probably one of the highest quality games of Marseillais ever played. Humans don't really know how to play it well either. Every aspect of standard Chess has been studied deeply for hundreds of years. But, as you saw for yourself when you went searching out samples games and analysis for double-move variants, there isn't much available. But stay tuned. This is an area that will hopefully see more development in the future. Now that there is a GUI that can run double-move games, hopefully some other chess programmers will make engines that are capable of playing them.