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ChessVA computer program
. Program for playing numerous Chess variants against your PC.[All Comments] [Add Comment or Rating]
Michael Nelson wrote on 2023-06-01 UTCExcellent ★★★★★

A much better player than Zillions. I notice that version 2.2 is scriptable, and the scripting language looks easier than Zillions' Lisp-based scripting language (which is a monumental pain in the a** to debug--all those nested parens). Does ChessV have a scripting reference? I'd love to see it rather than ask a thousand questions in this thread.

Aurelian Florea wrote on 2023-05-18 UTC

Hi Greg,

In the latest version I have the FEN does not contain anything about the last piece moved. The AI does not know how to checkmate in KJK.

[EDIT] I don't think I have the last version!

Aurelian Florea wrote on 2023-05-15 UTC

Hi Greg,

A while ago you have said that maybe you'll try to make two ai play on different threads, so that they'd play different parameters. A nice feature paired with that, would be the ability to force the set of parameters. Maybe some could still remain random, if they are hard to do.

Joe Joyce wrote on 2023-03-16 UTC

Hi, Greg! Thanks again for putting some of my games in ChessV. I deeply appreciate it. Gilded Grand Shatranj was a spur of the moment design, over the course of some minutes, quite literally exactly as it appears on the Grand Shatranj rules page, and almost that fast. That's the only write-up of it that I recall. If I actually wrote up all the games I've done while here as separate game pages, I'd show twice as many as appear here, or more. Many of the games are part of a series or variants of a particular game and/or style. Truthfully, many of my games are designed to illustrate the ideas as simply and easily and most familiarly as possible.

📝Greg Strong wrote on 2023-03-15 UTC

Thanks, Fergus. Been tied up by work as of late. Some of these have been pending description for a long time. Here's a quick summary:

  • Duplex Chess -- a new double-move variant that I've invented and need to document.  I wanted to make a balanced, double-move variant that wasn't too overwhelming.  This is managed in this game by the fact that no piece has a range more than 2, and the same piece cannot move on both of a player's moves ... with the exception of the King.  The King can move twice making him a viscous attacker.  (He can hit-and-run, unlike any other piece.)  But exposing him has risks, since if he falls, the game ends instantly.
  • Gilded Grand Shatranj -- this is definily a Joy Joyce original, but doesn't have it's own page.  The text on the Grand Shatranj you mention is probably the source.
  • New Zealand Chess -- From Pritchard's Encyclopedia of Chess Variants.  "Rook becomes Knight and N becomes R when capturing only.  R & P endings described as 'bewildering' (BCM Sep 1903)." Is all the info I have.
  • Nightrider Chess -- Also from Pritchard's Encyclopedia of Chess Variants.  V. R. Parton (1950s)
  • Odyssey -- This is mine, it's a complicated, ambitious invention that needs a page. 
  • Opti Chess -- This is a differnet capablanca-array with flexible castling.  Derek put it forward in comments probably close to 20 years ago now.  It turns out that this array works really well (in terms of most options for good openings.)
  • Relative Royalty Chess -- This is weird.  It grew from ICS's TwoKings variant, for which the rules were a random outcome of how ICS handled the presence of more than one king.  But "TwoKings" had problems (not surprising, since the rules were kinda random).  Relative Royalty Chess was an attempt to fix those issues.  I made it only because when first published, an enthusiastic user on Talk Chess loved TwoKings and wanted this.  I don't know if anyone plays it, or knows, or even cares.  Maybe it should go away.  But, if not, it should be documented.
  • Unicorn Grand Chess -- This is the Unicorn Great Chess pieces with a more Grand Chess setup.  (Pawns on the 3rd ranks, Rooks start connected on the 1st, pawns promote on the 7th by replacement under Grand Chess rules.)  This was my idea to adapt Uncorn Great in this way.  David ok'd the invention.  As much as I like Unicorn Great, I think this is even better.  Hasn't really been played here, but it has been built into ChessV for nearly 20 years.
  • Warochess -- This was emailed to me.  It was also submitted here, but if memory serves, it wasn't published on the basis that it was too close to other variants.
  • Wild Castle -- This is another thing to spring from ICS.  It's basically like FRC except there are only 18 setups.  (Rooks are always in the corner.)

🕸Fergus Duniho wrote on 2023-03-14 UTC

Since Greg hasn't responded to my earlier question, I went ahead with adding a ChessV tag to games playable on ChessV.

Here are the games on ChessV I did not find a page for here:

  • Duplex Chess by Greg Strong
  • Gilded Grand Shatranj by Joe Joyce (This is briefly mentioned on the Grand Shatranj page, but the description is too brief, and the Game Courier preset it links to has no landing page, does not describe the rules, and is not programmed to enforce the rules.)
  • New Zealand Chess by Unknown
  • Nightrider Chess by V. R. Parton (maybe it's in one of his documents, but it doesn't have its own page.)
  • Odyssey by Greg Strong
  • Opti Chess by Derek Nalls
  • Relative Royalty Chess by various
  • Unicorn Grand Chess by David Paulowich and Greg Strong
  • Warochess by Eric Warolus
  • Wild Castle by Unknown

With this complete, I have edited the header to use the ChessV tag to tell whether a game is supported in ChessV, and I have removed the Chessv column from the Item table.

🕸Fergus Duniho wrote on 2023-03-01 UTC

As a demo for how a ChessV tag could be used, I created and populated a Zillions OTB tag for games that come with Zillions-of-Games, and I added code to add an item to the Play menu for games that come with Zillions-of-Games.

🕸Fergus Duniho wrote on 2023-03-01 UTC


It appears your site doesn't support https. An easy way to fix this is to use CloudFlare for your DNS, as this site does. I have a free CloudFlare account that lets me use flexible SSL/TLS for free without hosting any files on this site.

Also, do you think it would be better to use a ChessV tag for games supported by ChessV? I created a column in the Item table for you to mark games supported by ChessV, but you haven't been doing that. I just marked Cylindrical Chess as supported by ChessV, and now the Play menu lists it as playable on ChessV.

📝Greg Strong wrote on 2023-02-24 UTC

The "variation" setting should not result in it making bad moves. The "weakening" setting certainly can if you turn it up. Regarding endgames, when the material gets down to only a few pieces, ChessV can have difficulty determining how to close the deal. I need to post a new build - I have made some definite improvements in this area.

Aurelian Florea wrote on 2023-02-24 UTC

I have observed that, too. I think it because it chooses among positions that are already winning!

Daniel Zacharias wrote on 2023-02-23 UTC

I've noticed ChessV making some obviously bad moves in endgames. Could that be due to the variation setting?

Aurelian Florea wrote on 2023-02-14 UTC


📝Greg Strong wrote on 2023-02-14 UTC

If you have at least one colorbound piece on each shade, there is a half pawn bonus. If you have two or more colorbound pieces on one shade with none on the other, there is a large penalty.

Aurelian Florea wrote on 2023-02-14 UTC


Have you noticed my previous comment!

Aurelian Florea wrote on 2023-02-13 UTC

@Greg, I have searched the source code and the documentation but I did not understood is the evaluation for the colourbound pieces pair is a bonus or a penalty. I need to know this in my bishops vs knights (for example) experiments.

Aurelian Florea wrote on 2023-02-02 UTC

I'll look into it more deeply hopefully!

📝Greg Strong wrote on 2023-02-02 UTC

Presumably, there was some reason that was not apparent. No way for me to say.

Aurelian Florea wrote on 2023-02-02 UTC

I've seen a game where a pawn has promoted to joker and not to rook for no apparent reason. Any insight towards why?!

📝Greg Strong wrote on 2023-02-02 UTC

The king has a value of 0.

Aurelian Florea wrote on 2023-02-02 UTC

Greg, what is the strength of the king used by the joker value evaluation?

Aurelian Florea wrote on 2023-01-31 UTC

Ok, HG, thanks!

H. G. Muller wrote on 2023-01-31 UTC

Short follow-up on posting diagrams: You must only write the board part of the FEN between the tages; the other stuff contained in a FEN would not be expressed in the image anyway. When I place your FEN between the tags I get this:

These are not the pieces you want; apparently the standard meaning for C is Cannon, for S Squirrel, and for J it is Camel. But that doesn't have to discourage you: you can either try an alternative likely letter (like M for Marshall), or replace the letter by the full name of the Alfaerie image in braces ({berolinapawn} and {fool}:

[ fen]3{FOOL}3k1w/10/10/8p1/2P5Pp/1{SERGEANT}7P/5{sergeant}4/10/4m4{fool}/7BK1[ /fen] gives


Aurelian Florea wrote on 2023-01-30 UTC

And because it was facing a difficult position white decided to go for a draw. Thanks Greg!

📝Greg Strong wrote on 2023-01-30 UTC

That's right. If white's last move was a chancellor, then it is a stalemate by either the old rules or the new rules.

Aurelian Florea wrote on 2023-01-30 UTC

White's previous move was by a chancellor from h8 to h10. That chancellor got captured. I now think I know what you mean, is what's the black joker's current power. The stalemate/checkmate status depends on that. And because the last moved white piece until white moves again is a chancellor that does not attack the king. We have a stalemate here.

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