The piece represented by the 'Ethel' rune could be considered a Crooked
Boar. The Boar in my variant Truffle Hunt Chess is also a colourbound
enhanced Ferz on the Pawn rank, but enhanced by the forward moves of the
Elephant with some pieces blocking it if on the intermediate cell. I
interpret the crooked form of a move along either forward diagonal as
alternating between the two, thus a Crooked Mitre would have half the
Ferz
moves, but only a quarter of the Crooked Bishop's non-Ferz moves.
	As a matter of general interest, my own use of Valkyrie is for a 3d
piece, a Rook that can also move exactly 2 cells diagonally OR
triagonally.

The piece represented by the 'Ethel' rune could be considered a Crooked
Boar. The Boar in my variant Truffle Hunt Chess is also a colourbound
enhanced Ferz on the Pawn rank, but enhanced by the forward moves of the
Elephant with some pieces blocking it if on the intermediate cell. I
interpret the crooked form of a move along either forward diagonal as
alternating between the two, thus a Crooked Mitre would have half the
Ferz
moves, but only a quarter of the Crooked Bishop's non-Ferz moves.
	As a matter of general interest, my own use of Valkyrie is for a 3d
piece, a Rook that can also move exactly 2 cells diagonally OR
triagonally.

I am witholding a rating until I get a chance to playtest it, but unless
there is some hidden flaw I expect to rate it 'excellent'. The game
concept is very innovative and I particulaly like those quirky Pawns.

Is anyone working on a ZRF for this game? If not, I will try it myself. 

If anyone is, you will need some code trickery--a straight forward
'capture both kings' type win condition will make Zillions very
hesistant to use the Valkyrie swap move on a King--during move evaluation,
Zillions erroneously considers this to be a loss of the King, though it
treats the move correctly when actually determining if the win condition
is achieved. Email me for details.

I will start development this weekend. I can use a coventional board and
piece graphics while I'm perfecting the implementation and substitute the
final graphics later. I might be able to derive the images I need from the
picture on the Web page, which looks really good.

By the way, Peter, I should have credited you with the indirect capture
target technique which I learned from you. It simplifies many complex
situtations as well as the king swap issue. It is, for example, essential
to the implementation of the Decima 10-points condition.

Garry,

I have a working ZRF implementing all the rules as you have given them on
the web page. Please send me the graphics files and I will finish the
implementation.

The Valkyrie swap is evaluated correctly when involving non-royal pieces,
only the swap with a King is problematic. The bug is in the evaluation of
win/loss/draw conditions within the consideration of the move: removing a
royal piece temporarily to replace it elsewhere is deemed a loss, whereas
after the move is executed and Zillions checks the conditions, it is
handled correctly. In other words, during a swap move, Zillions mistakenly
thinks the temporary disappearance of the King while it is being swapped to
another square is permanent.

In any case, the indirect capture target technique solves the problem.

One question: is it legal to use the Valkyrie swap to make a null move?
That is if a Valkyrie on c6 swaps the other Valkyrie at c9 back to c6,
then you have made a move but the position on the board hasn't changed.

In most CV's the answer is 'No', so I have coded accordingly: a
Valkyrie cannot swap positions with the other Valkyrie and a King using a
Valkyrie move connot swap positions with the other King.

If you intend to allow null moves it is trivially simple to change the
code to allow them.

Here is the 'Excellent' I thought I would be giving this fine game.
Having seen it in action while coding the ZRF, I am quite convinced of the
game's quality. 

The piece set is quite interesting and works well together. The Pawns are
unusual but easy to learn to use. The Pawns are quite strong: I'd guess
about halfway between a Ferz and a Knight (slightly closer to Ferz). 

The Forest Ox is the big gun of the board on both offense and defense. 

The Valkyrie is not quite as strong as the Forest Ox, but is much more
powerful than a Queen: the swap move allows if easier developement (can
swap with a Pawn in the opening setup) and more ways of escaping trouble,
while still having all of a Queen's move and capture power. 

Rook and Bishop are minor pieces, with the Rook the stronger but with less
gap between them than in FIDE Chess, since a Valkyrie swap can get the
Bishop to the opposite color.

The idea of the King's movement depending on the friendly pieces adjacent
to it works quite well here and I'd love to see it used in other
variants.

Overall, a highly playable and enjoyable game.

I am glad to hear that Michael Nelson's ZRF coding for Odin's Rune Chess
is going well. I am anxious to see the result.  Thank you Michael, for
undertaking the task. 

Michael wrote: is it legal to use the Valkyrie swap to make a null move?
That is if a Valkyrie on c6 swaps the other Valkyrie at c9 back to c6,
then you have made a move but the position on the board hasn't changed.

Michael is correct to not allow a 'null-swap.'  But also it is important
to note that the 'move/relocate' aspect does not mean the relocated piece
has to land on the start square of the Valkyrie [or King acting like a
Valkyrie]  it can be any square in that Valkrie piece's travel.  Someone
might then wonder, 'Couldn't the one Valkyrie relocate the other to a
square other than its start square?  Or the Valkyrie King relocate the
other King in the same manner?'   As for relocating the second Valkrie
[to other than the 1st Valkyries' start square] this would be the same as
if we simply moved the 1st Valkyrie to that relocate square, so it makes no
sense to do such a swap. Technically that move would be allowed; but there
is no point in it. 

Michael stated 'In most CV's the answer is 'No', so I have coded
accordingly: a Valkyrie cannot swap positions with the other Valkyrie and
a King using a Valkyrie move connot swap positions with the other King.'

Yes, that is the correct assumption.  But for other pieces note that it
need not be a position exchange.  The relocate square can be any through
wich the Valkyrie traveled, plus its start square. 

Another issue may need pointed out.  If one side cannot move, it is not a
stalemate.  The non-moving side simply losses. - gkg

An excellent and very enjoyable game!

A couple of questions, though.  Addendum item #2; I thought I understood
what was being said here, until the sentence 'Because of this rule, of
course, a King cannot do a 'move/relocate' function with the other
King.'  Why is this?  If King #1 is adjacent to a Valkyrie, can it not
make a move/relocate move like a Valkyrie?  And if the other King is
in-line, why can it not move/relocate that King?

Also, I assume that the Forest Ox cannot use it's optional riffle capture
to capture a friendly piece.  Correct?

Thanks!

This is to answer Greg Strong's good questions.  

Q1 ... a King cannot do a 'move/relocate' function with the other
King.'  Why is this?  If King #1 is adjacent to a Valkyrie, can it not
make a move/relocate move like a Valkyrie?  And if the other King is
in-line, why can it not move/relocate that King?
A1: The answer is that these would result in meaningless or 'null'
moves.  For example.

Imagine this set up on a certain file: Where '-' = space and
1 = King 1 and 2 = King 2 and V = Valkyrie.  

- - - - 2 - - - 1 V    Here, if a King (next to a Valkyrie) could relocate
the other, we could get:

- - - - 1 - - - 2 V    It is as if no move was made.  Or, we could get

- - - - 1 - 2 - - V    But this is positionally the same as 

- - - - 2 - 1 - - V   Inwhich we just moved King #1.

Note that Mike Nelson deserves the credit for initially realizing the
redundancy and null factors.  He discovered this while working on the
Odin's Rune Chess Zillions .zrf.  I agreed 100% with his conclusions and
his zrf rule implementations.


Q2:  I assume that the Forest Ox cannot use it's optional riffle capture
to capture a friendly piece.  Correct?
A2: Yes.  The Forest Ox only takes down the enemy, even when using its
horns for the optional adjacent square capture factor.

Note the the Odin's Runes Chess ZRF plays correctly by the rules so one
can get a good feel for the game using that (if he or she has a registered
copy of Zillions).

Thanks for commenting.

I have just completed a non-enforcing pre-set for Odin's Rune Chess.  It
can be reached via the following link.  The pieces retain the correct
orientation for black and white when the board flips.  This is important
because the pawns move in their depicted vector pattern.

/play/pbm/play.php?game%3DOdin%27s+Rune+Chess%26settings%3Dodin-runes

However, when king's move/relocate move is a null move it might be useful
to get out from stalemate-but I cannot give an example.
The game is really good!

Frank, thanks for the follow up comment. You write, 'My 'stalemate'
means any other move is worse than null move. Can you prove that's
impossible?'

Answer: Moves can be worse than null moves - such as moving your last
remaining King into a line of attack (legal in this game) and then losing
your last King and the thus game.  So, that a move can be worse than a
null move is a fact. But, null-moves are illegal in this game, and that
(and the fact that Kings are captured) is why we can't see a stalemate in
Odin's Rune Chess.

(c) a vacant cell which is under the influence of a pawn or piece (a projected gated piece)

The Valkyrie moves as does a Queen, but can essentially capture one of its own pieces and then relocate that piece to any space that the Valkyrie had just traveled through. Of course, the relocated piece was already on the board... so this would not be conventional gating.

.. so this would not be conventional gating.

Yes, it would seem to be a combination of (c) and (e)

'(e) be teleported to another cell on the board (example: castling).'

George takes it further by stating, 'The Castling comparison is apt among the 'a' to 'e' definitions of 'Gating'.'

Of interest is George's follow up statement,

'Castling is now-necessary encumbrance, complication, accepted widely in majority of CVs as making better play.'

And that sentence belongs in a book.

A question on piece names.

If this is Odin chess, a Norse god, why would there be a bishop piece,
which is a Christian 

Also is the Rune art available in other than bitmap, to make a set at
home?

thanks

Since the old GC preset for Odin's Rune Chess doesn't seem to work anymore, I've created a new one which can be accessed here.

Many thanks for the fix Erik, it is much appreciated. I was not aware of the issue. Regards, Gary

I am currently playing a game of Odin's Rune Chess, and I really like it, as much the rules and gameplay, as the runic theme. The Forest Ox is a terrific piece, maybe too powerful... I like the rather strong Pawns. I generally appreciate modern variants that use non-conventional Pawns, it effectively renews the dynamics of a chess game. And their initial colorboundness isn't a default at all, for me.

I was wondering if Pawn promotion could be integrated in this game - even if it is not necessary since Pawns can go back and the need for new material is less crucial, since the vulnerabiliy of the Kings without moving possibilities makes situations of insufficent material less likely. Promotion possibilities should be limited, since Pawns can reach the last rank in only four moves; for example, they could only promote to previously captured pieces of his own colour; or there could be limitations to the maximum number of pieces of each type present on the board (4 Valkyries, and 4 Forest Oxen, for example - which is already a lot). One can also think of the opportunity to permit the promotion to King (here too, the maximum number must be limited or promotion be only to previously captured Kings). But the game plays already well, I don't think it needs a promotion rule. I was just wondering how promotion could affect the gameplay, and if it could be interessant as a variant.

Edit: my comment about the possibility of promotion wasn't very pertinent. Promotion doesn't make much sense in this game.

I made a set, painted runes on back of some wooden Scrabble pieces. Painted board on some soft leather. Love the game. I might have just called it Odin's Chess, and I'd have opted for priests with some twist, but overall I like its uniqueness. It has a root chess feel but is very much a rebuild from that foundation.

There is (was) a Zillions version which grasps the game and plays it brilliantly. I lost all initial games to it... Thanks for commenting.

Why does it say stalemate is not possible? It seems the diagram of which it is claimed the best Valkyrie move is capturing the Forest Ox (Vf1xf7) actually leads directly into stalemate, through that move. After it black has no legal moves, and after hypothetical null move white cannot capture both his Kings at once, so he is not in check either. (And besides, the last black piece could have been taken elsewhere, so that neither black King would have been under attack.)

Seems clear to me. A player with only kings is forced to pass. "Checkmate" is not a thing. You just take the kings.

Vxf7 pass Vxg7 pass Kd6;-e6 1-0

But turn passing is not allowed in this game. If you read back on earlier comments to this game, one even goes so far as to state that when you can make pseudo-legal moves that would not change the board, (like using a Valkyrie's swapping move to swap it with your other Valkyrie), such a move would be illegal, because it is equivalent to a turn pass. Of course you don't even have such a move here.

In either case, since a stalemate draw cannot occur, the obvious conclusion, whether or not a king can pass, is that the side with a lone king (or 2 lone kings) loses, either by it/them being taken, or being unable to move.

I don't understand the phrase "Draws are possible; stalemates are not."  But in the addendum, point 3 is pretty clear:  

If you cannot make a move during your turn, you lose.

So the Vf1xf7 move H.G. brings up is actually a winning move.

Ah, I overlooked the addendum. So I guess what was really meant is "stalemate is a win". In fact stalemate is far more frequent here than in orthodox Chess. In the latter case the King has to be robbed of its legal moves by attacking all squares adjacent to it. Here you don't have to attack anything, as the King has no moves to begin with.

I guess you could also say that baring the King(s) is a win. But that is not the only way to get a stalemate. One or two Kings could block all moves of one, or even two Pawns.

Black to move is stalemated!

[Edit] This was very wrong; I failed to notice the Pawns also have backward moves. So I suppose the only stalemates are those where you have nothing but Kings.

The King has the simplest XBetza description of the unorthodox pieces: just xK to indicate it borrows moves from friends a K step away. The Pawn was straightforward, but gets a somewhat lengthy description, because both paths to the square two steps in front of it must be specified separately (because they bend in opposite ways).

The XBetza description of the Valkyrie uses the 'unload' operator for the moves that displace a friendly piece. There are two different kinds of such moves: a plain swap, which is specified as a simple move that unloads at the start when it captures at the end; the 'd' mode in udQ indicates friendly capture. (First-time use in a real variant!) Then there is a more complex move, that involves a third square. The diagram considers this a two-leg move with the unload square as intermediate. So you first have to click the square where the other piece is to end up, and then where the Valkyrie goes.

The Forest Ox is the worst of all. It combines a Knight move with a King-like rifle capture. XBetza cannot forge such different move types into a multi-leg move, so everything has to be reduced to a 'common denominator'. In this case everything is reduced to King steps, meaning that the initial Knight jump becomes two legs, where the intermediate square is made a don't-care w.r.t. the content of the square by allowing both moving and hopping. By using K as basic atom, each N square is reachable through two paths, but as neither is blockable that does not matter. After the first two legs for the Knight jump, two more legs follow for the rifle capture, the first making the capture as a normal capture in any possible direction, the second one to move back (cabK). Because of this description, one has to click the locust victim first, before clicking the target square of the Forest Ox.

I made a rule-enforcing Game Courier preset for Odin's Rune Chess. I chose this as a test case for the GAME code that the Play-Test Applet automatically generated, because it is notorious for having pieces with very unusual moves (causing side effects of various kinds). This makes it a good test for how such moves with side effects can be entered by means of mouse clicks. The preset can be found here.

There already was a preset for Odin't Rune Chess, but it did not enforce rules. It is still there, but now it doesn't even know the initial position, and shows the one for orthodox Chess. Last month that was different, so I don't know what happened to it.

Two modes for entering side effects

After some experimenting it became clear to me that there are two mutually incompatible ways to handle side effects with the mouse. Because mouse entry is limited to normal moves (i.e. defined by two squares, the origin and destination) and 'pass' (through the new button), but cannot be used to enter suicides or piece drops, everything has to be disguised as moves. For pieces like the Chu-Shogi Lion, which capture 'in passing' as part of a double move, the natural method is to just make the two moves: the first leg captures the piece, the second leg moves from the square where that happened to the final destination. If you want to stay at the capture square, you can pass the second move.

This way of entering moves turned out to be quite unnatural for the Forest Ox, which is described as a Knight that can make a piece adjacent to its destination disappear. This doesn't suggest the disappearence is the result of a double move, as the first move you would then have to make to get to the victim is often a very strange one (Camel or Zebra), different all the time, and how you then should get to the destination is very much dependent on where you came from. It is much more intuitive to consider the Forest Ox a Knight that can optionally make a King-like rifle capture as second move.

Something similar holds for the Valkyrie, which needs to drop a piece (the friend it just 'captured') as a side effect, rather than remove one. It also feels very unnatural to first have to move to an empty square to 'mark it for unloading', and from there perform a swap with the piece at the destination. It is much more intuitive to just capture the friend you want to displace, and then select the square where it should go to.

To accomodate that, the GAME code can be configured by defining an array shooters', containing the piece types for which side effects have to be entered after the main move. In this preset for Odin's Rune Chess this is set like

set shooters (Q q N n);

because both the Forest Ox (N) and Valkyrie (Q) fall in this class. For such pieces you always move them directly to their destination. If the move has / could have a side effect, which is not yet unambiguously defined, you will be prompted for that side effect. You can then click the just-moved piece again, to turn on highlights of the squares that could be affected by the move, and click the square where you want to apply the side effect. For a Valkyrie friendly capture this would then put the captured piece there, for a Forest Ox it would remove the clicked piece. If the side effect is optional, and the move could be made without one, you can click the Pass button.

Pieces not mentioned in the shooters array will behave as double movers, which should first be moved to the square of the side effect, and then to their destination. If the side effect is not possible on the destination of the first move (e.g. because the side effect is a capture, but the square is empty) it will be considered the final destination right away. If a side effect at the first destination is possible, but the move itself would already be pseudo-legal by ending there without side effect, the Pass button can be used to leave it at that. Otherwise you just click one of the possible final destinations, after switching on their highlights through clicking the moving piece again.

If there is a single mandatory side effect (such as when the Valkyrie captures an adjacent friendly piece; then it has to swap places with the Valkyrie), the user will not be prompted for a side effect, but the move will be auto-completed instead.