Comments/Ratings for a Single Item

I think it's a bit too late to start using the name Chess2. There are already numerous Chess variants, and you wouldn't be the first or even second person to use the name. Pritchard mentions a Chess Too and a couple Chess IIs, and there is a commercial game described on this site that was called Chess 2 - The Sequel.

The game ends in stalemate if at the start of his turn a player is not in check and has no available legal two move turns and no available legal single move turns.

I'm not sure how to interpret the part I put in boldface. Which of these do you mean?

1. If a legal first move is not available, but a second move could remove any checks caused by the first move, it is not stalemate.

2. If there is a legal first move, but it cannot be followed by a legal second move, it is stalemate.

3. If a player cannot make a legal first move, it is stalemate.

(Note: my answer below is not clear and not quite correct. It is also out of date--the rules have been renumbered and it should now refer to rule #2. Please disregard this answer and see the full rules and subsequent discussion above.)

Okay, I see that I need to clarify this rule. To answer each of your scenarios:

1. By rule #1, each move of a two-move turn must be individually legal for the position on the board at that moment--it does not matter whether a second move could remove any checks caused by the first move. So if there is no legal first move, it is stalemate.
2. This is stalemate.
3. This is also stalemate.

Would this wording be more clear?

The game ends in stalemate if at the start of his turn a player is not in check and cannot complete either a legal two move turn or a legal single move turn.

This is a fair point. I am open to suggestions on the name. Initially I wanted to use the name "Double Move Chess" and was quite disappointed to find that the name was taken. I clearly failed to do another search, as I was unaware of "Chess2 - The Sequel" until now.

I like "Chess2" because of the double meaning of it being the second version of the game as well as it being characterized by two-move turns. The alternative "Chess2.0" would sort of lose the second meaning.

But you're right, this needs a new name. I will try to think of a better name, and again, suggestions are welcomed!

Thanks.

2 Move Chess?

By rule #1, each move of a two-move turn must be individually legal for the position on the board at that moment--it does not matter whether a second move could remove any checks caused by the first move. So if there is no legal first move, it is stalemate.

I think you're saying that the first interpretation is incorrect. If there is no legal first move, it is stalemate.

Would this wording be more clear?

The game ends in stalemate if at the start of his turn a player is not in check and cannot complete either a legal two move turn or a legal single move turn.

No, it just applies De Morgan's theorem to what you originally wrote, leaving the original ambiguity intact. Since the third interpretation could be put succinctly and unambiguously as "The game ends in stalemate if at the start of his turn a player is not in check and has no legal first move," I think you favor the second interpretation, which I think is more clear when worded like this:

The game ends in stalemate if at the start of his turn a player is not in check and either has no legal move or, if he does have a legal move, cannot complete a second legal move after the first.

It seems that you favor the second interpretation, which is that the player must be able to make two legal moves to avoid stalemate. However, what if the first move is one that would normally prohibit a second move, such as a check, a promotion, a capture, or a double Pawn move subject to en passant? Would it still be checkmate in that case?

Okay, let me see if I can explain my thinking here. The terms "turn" and "move" are not interchangeable in this game. The rule for stalemate could be stated most simply as: the game ends in stalemate if at the start of a player's turn he is not in check and cannot complete a legal turn.

To break that down, assume that the player is not in check. At the start of his turn the game is in one of two states:

1. His opponent has just made a single move. In this case he must make a response move. Since this is just one move, the possibility of stalemate is evaluated exactly as in international chess.
2. His opponent has not just made a single move, so he may take a two-move turn (if possible) or a single move turn (if possible). Keep in mind that the set of moves that could comprise the first move of a two move turn is disjoint from the set of moves that could be played in a single move turn. If none of the moves in the first set can be followed by a second legal move, and the second set is empty, the game ends in stalemate.

When you ask above, "what if the first move is one that would normally prohibit a second move, such as a check, a promotion, a capture, or a double Pawn move subject to en passant?" you are asking about a possible single move turn. It is not stalemate if any such move is available.

I am trying to be succinct, and yet it seems I need to provide more detail here.

That's a great suggestion! I might be more inclined to "Two Move Chess", but I like it either way. Thanks for the suggestion.

I have just edited the rules. I split them up into more numbered items, and (I hope) added clarifying language. Thank you for the comments and questions. Please take another look.

I am still pondering the question of the name. If I change the name, will the URL change? And if so, would we lose these most excellent comments?

Thanks.

Ted

I am still pondering the question of the name. If I change the name, will the URL change? And if so, would we lose these most excellent comments?

The URL will change, but I can manually update the database to keep the comments with the page.

After some thought, I would like to change the name of this variant to "Two Move Chess." If it's not too much trouble, it would be nice to rename it while preserving the comments.

I have gone over everything again and made additional minor edits that I hope clarify the rules. I have also added an example of stalemate in the Notes section, and added a note at the start of one of my earlier comments that was both unclear and incorrect, letting people know that they should disregard that particular comment.

Thanks again for all of the comments, questions, and suggestions below!

Ted

Actually, maybe it's better to let the comments go. I can create a new submission with the name "Two Move Chess" and delete this one. Earlier I was thinking we should preserve the comments to give credit to both of you for the clarifying discussion and for the suggested name change, but I also don't want to make extra work. What do you think?

Thanks.

Ted

I haven't been following this conversation, but I was in the same situation. Create the revised game using the new name but put links into it to the original page, and edit the original page to link to the revised rules, with notes that the original is being kept for the history and comments. One page more or less won't make that much difference to this site. And you haven't disappeared all that work.

Patience. I will get to changing the name.

One page more or less won't make that much difference to this site.

I completely disagree with this.  Yes, there is a lot of clutter that should be cleaned up.  And, from time-to-time I do make progress on that.  But step 1 is not to make the situation worse.

Actually, I agree with the idea that one page more or less per person makes a noticeable difference. I meant literally 1 page, kept for the specific comments and discussion, done by the few people who do wind up with a separate revised version. And it's kept for the discussion.

It's a personal thing with me. I hate seeing information lost. I argued with everyone from John Smith to Derek Nalls about deleting games. I lost both those particular arguments, and lament it. Both had interesting stuff that they later decided didn't live up to their standards.

But I admit to being surprised at how many game courier settings files I have. Some of them can go, being early attempts at something I did better or gave up on. Some are non-chess prototype designs used for playtests of other people's games. Game Courier can handle a lot of abstracts besides chess variants. Should they go, too?

I have now updated the ItemID and the game's name in the database.

Thanks for updating the name of this variant in the database, Fergus. And thanks to everyone for the additional comments below. I have added a paragraph to the introduction to explain the motivation of the design. I hope this will make it easier to understand the reasoning behind each of the rules.

This submission is ready for another review. My hope is that it is now ready to go!

Thanks.

Ted

I modified the rule regarding notation, because the rules of a game cannot specify the notation to such detail unless they are for a specific tournament or something like that. Some games are recorded with different kinds of notation, and software like Game Courier or Zillions-of-Games will use their own style of notation for all games.

I unhid this page, but I did not examine the notes section in detail.

This is an interesting and logical approach to tackling how to have a double-move variant addresses pesky rules like check and en passant.  They always require special-case rules to address, and how it is addressed here "feels" right to me.  Marseillais Chess handles the check thing fine, but falls down on how en passant is handled.  You seem to have neatly solved that, too.  I also like how you are limited to one capture per move and cannot move the same piece twice.  This also helps to preserve the strategical similarity to orthodox chess. I guess Marseillais is more of a "let's make double moves and we'll end up with an interesting but totally different game."  Originally, it wasn't even "balanced" (white started with two moves.)  This is an ambitious attempt to add the property of double moves games being "balanced" while changing as little else about the game as possible.

Extra Move Chess also provides similar benefits.  You can make a second move, but don't have to, as long as it doesn't capture or move a piece that just moved.  If you make a second move, it can be a two-space pawn move (which a first move can't, except for white's first move of the game.)  This also neatly solves check and en passant.

I'd like to add this to ChessV.  I think it's doable but I need to think some things through.  The thing I see that most concerns me is this:

Each position created by a two move turn is included in the count toward a draw by threefold repetition, or toward a draw by the Fifty move rule (or the Seventy-five move rule)

If I understand this, it would be difficult to implement and doesn't make a lot of sense to me.  Are you saying that any move in a single move turn or responsive move turn should not count towards the 50-move rule, nor should they be counted toward any potential repetition?

Thanks, Fergus. I see your point about notation. Upon reading it through again, I think it would be more clear if the rule explained up front that it is just about notation. I'd like to update the first sentence to say, "When recording a game, a two move turn must be clearly distinguished from the moves of the other player."

Thanks for your review, Greg. You have understood the design perfectly, and I would be delighted if you added Two Move Chess to ChessV!

After some thought, I see that the rule for three-fold repetition should be handled differently than the 50 move and 75 move rules. Let's take them one at a time.

For threefold repetition, let's consider the game to be a sequence of board positions. A two move turn results in two positions, while single move and response move turns result in only one. It doesn't matter what type of move produced each position--a player may claim a draw by threefold repetition simply by noting that a certain position has been reached for a third time (with the usual considerations of whose turn it is, what castling rights exist, etc.).

For the 50 move and 75 move rules, I think the simplest resolution would be to change them to a 50 turn rule and a 75 turn rule in Two Move Chess, with the reminder that a turn and a move are not equivalent.

I am open to other proposals, for example these rules could be replaced by a "25 turn rule" and a "38 turn rule", but I am inclined to think that would introduce unnecessary confusion.

I've updated the rules, separating the rule for threefold repetition from the the one for a 50 turn and a 75 turn rule. I've also made the change I mentioned below for the rule on notation. (One could argue that a description of notation doesn't really belong in the rules section, but I'll leave it there for now.)

Thanks.

Correct me if I'm wrong, doesn't rule 3 imply that a player with a bare king is stalemated, even if he has legal moves, since he's not allowed to move his king twice in the same turn?