Okay, I'm not much into westerns, but I guess it means in this context, the group of pieces trying to checkmate the King.

> I'm guessing H.G. actually meant to spell the word 'posse' instead, i.e. use one more 's'.

Ah yes, I am sorry. It is a word I only know from watching westerns, and I had never seen it written down. Of course I should have known that 'pose' according to English pronounciation rules would sound different, and actually is an existing word. I corrected the spelling now in my original posting, thanks.

I'm guessing H.G. actually meant to spell the word 'posse' instead, i.e. use one more 's'.

This is interesting, but I don't understand what the word pose means in this context.

When programming is involved one can never be completely sure. But it is what the EGT generator says, and that same generator gives exactly the right statistics for the conventional pieces (where other EGT exist to compare against). The number of positions at each DTM then is exactly the same.

What I am sure of is that the argument you give is not relevant. What is relevant is whether the bare King can outrun the 'posse' that tries to drive it in the direction where it doesn't want to go, and run circles around it. If the mobility of the exclusion zone created by the attacking pieces is larger than the speed of a King, the latter is effectively trapped on one side of it. The point is that the board has edges. So it is enough if your posse can keep up with the King when it stays running in the same direction. Because eventually it will be blocked by an edge, and will have to reverse. Which takes some extra moves before you have to start keeping up with it, which can be used to make progress. E.g. King + Bishop + something vs King: King + Bishop can confine a King in a triangle at a corner, because the attacking King can plug the hole where the bare King could slip through the Bishop diagonal. But is just moves fast enough to keep doing that. But when the bare King has to reverse because it hits the edge, it now needs two moves before it threatens to escape, so you have one spare move to approach your third piece. Eventually it will then join the posse, and force the bare King to step back rather than just reversing, at an edge. This will work on a board of any size.

But when the speed of the posse is lower than that of the bare King, you can no longer confine the latter when the number of moves it needs to gain the width of the posse is smaller than what the posse needs to cross the entire board.

P.S. The entry form throws away long stretches of text again. Luckily I has moved this one to the clipboard before pressing 'Preview'....

Are you sure?  It does not make sense to me why a mate could be forced on 10x10 but not on 12x12.  Both sizes are much, much larger than the max range of either piece (range 2).

Thank you H.G.

Now I can rest assured that for a 10x8 variant idea I'm toying with, a Champion can always force mate, while for Gross Chess' 12x12 board it cannot.

Yes, I can confirm that (from end-game tables). Champion can force mate only on boards up to 10x10.

Short-range leapers (i.e. up to distance 2) that cannot force mate without King help must in general lose their mating potential when the board is made sufficiently large. For pieces like WFDN it would not be a problem, and even WFvDvN could force mate on any size board. (But not on an infinite quarter plane, as it cannot catch up with a King running sideways.) But less powerful pieces cannot hinder the King enough to allow the other King to catch up with it.

I'm not quite clear on Fergus' statement on this game's page: "While it is possible for a King and Champion to checkmate a lone King, this will usually require cooperation, which may make the Champion as ineffective as a minor piece in the endgame."

Has this assertion (to paraphrase, mating with K + Ch possible, but not always forced) been previously confirmed somewhere? If it is true, is it as stated not the most normal case that mate can be forced on any reasonable sized square/rectangular board?

This game is really sweet for a quite large (12x12) variant, and as advertised it has a small learning curve. Lots of fun!

Ok, I understand :)!

Checkmate with a Knight and Vao looks like this. It might not be possible to actually force it.

I suspect that the table only lists what is 'insufficient mating material' in the sense of FIDE rules, namely that no mate position exists at all, not even a help-mate, and that this immediately terminates the game as a draw. I cannot imagine that you could force mate with Knight + Vao. (But my EGT generator doesn't do hoppers, so I cannot say that with mathematical certainty.) It is already very hard to drive a bare King in a corner with Bishop + Knight, while the Bishop can attack lots of squares without a screen. Once trapped in the corner of the Vao shade by King and Knight, it would be possible to checkmate the bare King in a corner (say a1) with the Knight on c3, and the Vao on the main diagonal.

I'm not sure about the knight+vao checkmating tehnique in this game, may someone guide me?

I was aware of this variant and was also recommended this variation by Fergus Duniho himself when posting about my own apothecary games.

I'm glad that someone has thought about the weird promotion before me so it means I'm not that crazy. Even if aware of the variant, I utterly  forgot where I have took the weird promotion rule from, was it from my own mind or was it another variant. Anyway it is great that we can play a game that has a similar promotion rule to my apothecary games. Although in apothecary there is no concept of holdings.

The moves of most pieces are not very special, and have very basic descriptions in Betza notation, all supported by the Interactive Diagram script. The main challenge was in the promotion rules. The diagram allows you to specify a list of legal promotion choices, and even allow you to specify that these pieces come from holdings that accumulate captured pieces, as well as some pieces that start there. But has no standard mechanism for making this choice rank-dependent. For this a small extra script routine had to be added, which corrects any invalid choice to a non-promotion.

The flexible castling is achieved in the diagram by specifying all possible different castlings as separate moves on the King: isO2, isO3 and isO4. This is needed because unlike with other Betza atoms, a range specifier on the O atom in the XBetza extension used in the diagram indicates an exact range, rather than a maximum. That the castling partner is not at the board edge poses no special problem, because the diagram always allows castling with a virgin piece that moves as a Rook. (Which actually is in violation of the XBetza specs, which would need an extra j modifier to specify the castling partner is one square away from the board edge. But which is almost always what you want.)

Regarding the comments below, I'm not seeing how being 'simply' an amalgam of some well-known chess variants makes this a 'less interesting' variant. Not every variant needs to have some completely radical twist, and for my money I find variants that aim to be 'natural extensions' to chess much more relevant to my personal interests.

I find myself quite partial to the particular concept of this variant myself, and I feel that the twelve different pieces complement each other fairly well. I would be interested in seeing another variant that utilizes the exact same pieces in a different setup for a possibly even tighter game.

Since inventing this game 7 years ago, I haven't been very active in creating new games. While part of this is due to having distractions and other interests, it's also because I have been very satisfied with this game. Instead of being an exploration into new territory, which can be an iffy prospect, this game takes what I like about Chess and increases it to a larger scale. Using the guidelines I set out in an article called On Designing Good Chess Variants, it stands up very well.

Playability (Simplicity + Clarity) & Interest (Depth & Challenge)

Because it uses familiar pieces, it is easy to learn, and because of its size and its number and variety of pieces, it offers great depth and challenge. Despite its size, the pieces move in fairly straightforward ways, which makes it easy enough to understand and evaluate a position. One of the reasons I like Chess much more than Checkers is its variety of pieces. Having different pieces makes exchanges more interesting. With this game's several more types of pieces, it has a greater variety of possible exchanges than Chess has. This increases the odds of uneven exchanges happening, where players exchange different pieces. This allows for a greater variety of unequal armies that might face each other during the course of the game.

Enjoyment (Excitement, Decisiveness, Duration, Satisfaction)

As inequalities develop between sides, the game can become more decisive, yet because of the greater variety of pieces, it may be harder to call the game during the mid-game, which can make the game more exciting. Although the large size of the game could delay attacks, the Cannons and Vaos enable attacking even before pieces have made it across Pawn lines. This allows the mid-game to start even sooner in this game than it might in other variants of this size. This makes the game quicker and more exciting from an earlier stage of the game. The triple Pawn moves and the three-rank promotion zone also help speed up the game, which is important for a game this size. Because the game is like Chess in demanding skill, and its larger size and greater number of uncertain exhanges increases the opportunities for players to make mistakes, a player who wins should feel satisfied at winning, and even a player who loses in the end may feel satisfaction in how he played the game.

Fairness (Balance + Control)

While moving first can give White an advantage, I think this advantage diminishes as a game grows larger, and it is also lessened between opponents who have not yet mastered the intricacies of the game. Also, this game offers no particular weakness for either player to exploit early in the game. All pawns start out protected, and most pieces can move someplace else even from the opening position. Because no piece is stronger than a Queen, there are no end-game surprises from a powerful piece like an Amazon getting loose. The game remains a team effort between different pieces rather than one where a star piece takes over. As with Chess, both sides start out equal, and the outcome is determined by the skill and choices of the players.

Five of the additional pieces in Gross Chess come from some of the most widely popular of Chess variants, and a few of them have been widely used in many variants. So they are very well known enough that including them doesn't add much to the learning curve. The remaining piece is just the diagonal version of one of the first five, and Eurasian Chess, which I also use the piece in, is still more popular than Xhess. Also, the games Gross Chess is based on are each natural extensions of Chess, and by combining them, Gross Chess is just an even larger-scale natural extension of Chess. But Xhess is not a natural extension of Chess. It is a step in another direction. To replace some Pawns with Horsemen just does not fit with the theme of this game. It also tampers with an important element of the game and could potentially ruin it.

If you want to make a Chess variant that uses Horsemen, you are free to do so. But I will not be making a version of Gross Chess that includes them.

I suppose in my view since you are using pieces from a couple of sets, you
easily have two pawn styles to facilitate altering a pawn array

and in the case of horseman the move is basically a sliding knight move so
the learning curve is low.

it is also rather likely only somewhat seasoned players are going to try a
game such as this, you are after all assuming they have played Xianqui,
Omega, Grand (of a similar variant) and know about the Vao piece, or if not
have to assimilate 6 pieces, that while more or less extensions of the base
western game, are still different.

That already assumes a rather large set of variables associated with the
game.

I understand that

But I do find variants reluctant to change pawn array yet it's half the
pieces.

In this case would lift game beyond a simple amalgam of other games which
are generally already accepted as great variants Grand/Omega etc


Just M2C

If you do revamp to smaller.

The Horseman from Xchess (
http://www.chessvariants.com/large.dir/xhess.html ) rather than pawns might
add a rather interesting touch

'This piece was inspired by the Cavalier from Fergus Duniho's Cavalier
Chess. It moves like a combination of a orthodox chess pawn plus a
non-capturing Horse (from Xiangqi), but can only move forward and cannot
leap other pieces. No en-passant or initial two-move. Normal chess-type
promotion.'