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Extra Move Chess. Double-move variant based on limitations of Zillions of Games. (8x8, Cells: 64) [All Comments] [Add Comment or Rating]
Johnny Luken wrote on 2015-04-03 UTC
I had dabbled with the idea of a 1/2/2/2... multimove variant, if only as it negates white advantage.

The restrictions you introduced make this one of the most well refined multimove variants I've seen.

While an interesting alternative to FIDE, this mechanic probably improves most larger variants outright.

Fergus Duniho wrote on 2015-04-02 UTC
Thank goodness I wrote the notes on this game when I made this page ten years ago. It helped me figure out what my ZRF code was doing, so that I could fix a bug I just discovered recently. The bug concerned the code I wrote to make blocks made on the second part of a move ineffective. It inadvertently allowed a Rook check when the checking player's last move was to move a Pawn forward. It now checks the side of the piece last moved, confirming that it belongs to the other side, and it now blocks checks on the space the last piece to move moved from.

The ZRF still allows a player to make moves that do not end check on his King. But it's because of this limitation that the rules and ZRF are designed to prevent the second move from effectively rescuing a King from check. This assures that any first move that leaves one's King in check will automatically end the game in checkmate. Game Courier can stop this, but when playing Zillions, it's up to the player to not accidentally move into checkmate. Of course, with Zillions, the player has the option of undoing his move and continuing on.

Fergus Duniho wrote on 2011-02-01 UTC

I just made a video on Extra Move Chess tonight:

Jeremy Good wrote on 2009-11-16 UTC
Just want to report: I was, in fact, able to move when I tried today - not sure what the problem might have beeen - whether with me or something else. If I recall correctly, I had been getting error messages when I tried to enter any move. But if I'm wrong, perhaps I was trying to enter an illegal move, like a check or capture on the second move, most likely. At any rate, I appreciate your work you've done on this and the attention you've paid to it, with apologies if I misdirected it. Regards.

Fergus Duniho wrote on 2009-11-15 UTC
Jeremy's problem is not on the first move, and it has occurred after I fixed the code.

Nicholas Wolff wrote on 2009-11-15 UTC

I want to point out that it is, in fact, legal to move a pawn 2 squares on White's first move.  It states in the rules (#3):

You may move an unmoved Pawn two spaces forward only on your second move or on White's very first move. 

When I was trying to make my moves, not only was the double step on my first move illegal (as white), but also all the single steps and knight moves.  I had no trouble after you modified the code, but as Jeremy just said, he is having the same issues.

Fergus Duniho wrote on 2009-11-15 UTC
I tried some moves and got the same problem, then tried some other moves without any problem. At first I thought the problem might be pieces crossing each other's lines of movement. But the problem turned out to be that I was making an illegal move. I was trying to make a double Pawn move as your first move, which is illegal. Is that what you were doing?

Jeremy Good wrote on 2009-11-14 UTC
We were able to make a couple of moves in our current game but I wasn't able to make another move just now.

Nicholas Wolff wrote on 2009-11-13 UTC
Thanks, Fergus!

I will check it when I get home.

Fergus Duniho wrote on 2009-11-12 UTC
I have now fixed the preset for Extra Move Chess. Changes I made to the eval command had caused the code to stop working right. I fixed the eval command and debugged some optimizations I made to the Extra Move Chess preset. I then tested it on all past Extra Move Chess games, and they all worked fine.

Fergus Duniho wrote on 2009-11-11 UTC
It appears that the bug in Extra Move Chess is due to changes I made to GAME Code's eval command. When it evaluates a move, it is not setting the variables that normally get set when a move is made.

Nicholas Wolff wrote on 2009-11-10 UTC
I can't make any moves in a game.  I am white and it is my first turn.  I always get this error:

79: die You may not move the same piece twice on the same turn.

It also lists a bunch of 'arrays'?


Jeremy Good wrote on 2006-02-24 UTCGood ★★★★
Because of the compulsion to move out of check on the first move combined with the restriction that capturing can only take place on the first move, double checks and the threat of double checks are extremely powerful in this game and they can be produced more easily than in regular chess when they are only borne out of discovery. Offensive play should be more successful in this variant than defensive play.

Greg Strong wrote on 2005-08-30 UTCExcellent ★★★★★
Yes, this game definitely deserves the rating of 'excellent.'  I am in
the middle of my second game against Fergus, and I've seen enough to be
confident in my assessment.  I love Marseillais Chess, but I think that
this game is a significant improvement.  Although many of the restrictions
added in this game are related to facilitating computer play, I think the
rules added are an improvement even for human play.

Marseillais Chess has a couple of problems, in my opinion.  For one thing,
I think the game suffers from the fact that although the double-move aspect
makes the game sharp and violent, you still have to cower well behind the
enemies' pawn line... Because the same pawn can move twice, including a
double-move on the first move, you have to hide all your pieces on your
first three ranks; otherwise you sacrifice them to enemy pawns which are
extremely viscious, especially if they have not moved and thus are
elegible for an initial double-step move.  Also, the double-move aspect
makes riffle capture possible, and thus makes the game very aggressive and
unstable... which I like, in general, but you still have to run and hide so
a mere pawn doesn't run you down.

Also, when the pawns start advancing across the board, and the game begins
in earnest, the ability of any piece to move twice, and thus to conduct a
riffle-capture, leads to a highly tactical game wherein the material drops
like crazy, minimizing the strategy ...

Extra-Move Chess prevents the same piece from moving twice, and eliminates
the possibility for two captures on the same turn.  I believe that these
restrictions make for a more strategical game, while maintaining the speed
and excitement of other double-move variants.  I highly recommend this

Michael Nelson wrote on 2005-08-30 UTCExcellent ★★★★★
Sometimes the limitations of our tools are helpful--here by designing to the limitations of Zillions, Fegus has produced a superb double-move game: quite possiblly the best of the genre. Highly playable and the effective power of the armies is meaningfully higher than orthochess but significantly lower than other double move variants. A sharper, bloodier and more tactical game than orthochess--but still has room for strategic play.

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