I modified the sentnences

I think you can omit "the type and number of pieces captured in each other", as in a game without drops this must be the same if the position on the board is the same.

Ah, I fixed them. Thanks !

// Even if there are only two Kings left on the board, the King closer to the enemy camp wins in the end, as the same situation cannot be created more than three times.

// About threefold repetition :

If the same situation occurs 3 times with the number, type, and location of each other's pieces remaining on the board, the player who created the situation loses. Simply put, no player can create the same situation 3 times in one game.

 - Even if it does not appear in a row, if the same state occurs 3 times in a game, threefold repetition is established.

 (Of course, it is also impossible to repeat the check consecutively.)

You write the variant does not have piece drops, but then you write: " The player who can no longer move or drop pieces loses".

It is not clear what you mean by 'situation' in the description of the repetition rule. Is that just the same board position, or does it also mean the same player has to be on move? When you write the 'after it occurred twice no one can repeat the position again' you suggest that it does not matter who has the move. Because one it does, only the player that created the position for the first time could recreate it.

And about the absence of a 50-move rule: it it really your intention that when an endgame of King versus King results the players should go on until one of them gets stalemated by the ban on repetition? That seems awful.

The ascii diagram of the initial position seems redundant. And wrong too, because there is a Templar in there.

Can this be republished ?

Yes nice! I suggest to add a definition for "cardinal". Is that synonym of Orthogonal in this context? Maybe some diagrams would help understanding the moves. I have seen a typo : heaens. Why these name of Imp and Fiend? I have to check, I don t know these words in English.

I've fixed the file names, alongside a few formatting bugs and making sure pawns don't share a letter with any other piece.

While I understand why Earth got the a-h files, I would suggest giving them to the skies, while Earth gets the middle ones (j-q). This makes the files be in alphabetical order when the board is setup, and as an added nice bonus, the "missing" files i and r keep the color alternation. vg a1 white, b1 black, ..., h1 black, (i1 white), j1 black, ..., q1 white, (r1 black), s1 white, ..., y1 white, z1 black.

Nice!

It's particularly interesting how some of the 1-piece endgames (rook, angel) end up looking like a classical one to force the king out of Earth and then having the friendly king deliver the final attack. (The angel's isn't completely clear to me, since the lone king may move to the underworld early to avoid the angel's attacks, but I guess that's a significant enough detriment that then the friendly king can manage on his own.)

That helps, yes. To be explicit about the "last" question in each case then, the answer is "not"? My piece on a4 (1) cannot be captured by and also (2) blocks movement (to a1...3) of an opponent rook on a8?

Thanks Ben for the questions, here it should be clearer in the description (although it is already described between the lines, but that is probably not enough).

When capturing on a switch, first assume that there can be only one piece on a switch (here I differ from Fergus Duniho's Reroute66, a variant of my idea). So, for example, if a rook or queen starts from a1...a3 or from rank 4 and the switch is not occupied, then either square 4 or square a4 can be occupied in the switch.

But there is no choice if the switch is occupied by a piece. If a rook or a queen moves from a1...a3 or from rank 4 into the switch, then the piece in the switch must be captured (because two pieces on the switch are not possible). If the piece was on square 4, then the opponent's piece is on square 4 after the move has been executed (applies to a4 in the same way).

Furthermore, an occupied switch cannot be jumped over and a direct change from 4 to a4 (vice versa a4 to 4) is not possible - differently in Reroute66.

Have I understood the question correctly and hopefully answered it correctly? I would be glad.

I didn't really follow the discussion on this variant earlier, but gave the page a fresh read. I think I mostly get it now, except how capturing on a switch works. It might be clarified in the comments, but it should be made plain in the page text as well. (Perhaps it is there too and I have missed it and/or it wasn't quite clear enough.)

Let's say I have a piece on 4, and the opponent has a piece that can otherwise move to a4 but not 4. Can they capture (and if so where do they end their move) or not (if not, could they potentially continue moving through a4 past my piece? I'm not sure that makes sense for any piece at the edge of the board like this, so probably moot, but I'll ask in case)?

Same question reversing 4 and a4. (Now the last question certainly can apply, e.g. the opponent piece is a rook on a8.)

Interesting! Creative! Insightful! I do have one small thought: would you consider transposing the courier and the knight? The knight would then be in its usual position, where expert players use it to contest the center and protect the king and queen. The bishop, a long-distance runner, would probably do just as well near the edge.

I just noticed the question (only 6 years later). I think the stronger player will win. Here is a game with notes:

1. d4 d5 mandatory first move

2. g3 Nc6

3. Bg2 e6
   Pawns only move 1 space, except for the first required move (1. d4 d5)

4. e3 b6

5. f3 g6

6. Kf2 / Hia e1 . . . White Hia goes to e1 (mandatory) 6.. . . . Bg7

7. b3 Ba6

8. Bb2 Nge7

9. c3 Kd7 / Hia e8

10. Nd2 Kc8

11. Nh3 Kb7 As there is no castling in Shatar, Tony moves his King manually to reach something like a Queenside castle. He moves his King to b7 to free the Rook on a8 for his next move.

12. a3 Rc8

13. a4 Hia d7 Neither player is used to the Hia but they know it is a great defensive aide to the King. Tony moves his towards the Black monarch.

14. b4 b5 Timmy wanted to pawn-fork the Bishop and Knight. Tony played b5 to stop it.

15. axb Bxb5

16. Qc2 Ra8

17. Hia e2 . . . Black can’t capture the Hia with his Bishop as he’d have to stop at d3 due to the Hia’s protective field. . . . a6

18. Ra2 Ra7

19. R(h)a1 Hia d6

20. e4 dxe

21. Nxe4 . . . attacking the Hia . . .Hia d7

22. Nc5+ Kb6

23. Nxd7+ exchanging Knight for Hia . . . Qxd7

24. Hia d3 . . . Annoying, the Black Bishop can’t take the Hia . . .Rha8

25. Qb3 e5 Struggling for counterplay

26. d5 Nxd5

27. c4 Bxc4

28. Qxc4 N(d)xb4

29. Qb3 a5

30. Hia c4 Bf8

31. f4 Bc5 (This is not a check due to the Hia)

32. Bxc6 Kxc6

33. Ra4 Nd3+
    Remember that Knights are immune from the Hia forces but Hias can still capture Knights. Here the Hia can’t capture the Knight because that would activate the Bishop’s check (from c5)). White playing 34. QxN would be a blunder because Black would play 34….QxQ and the Hia could not recapture due to the Bishop check factor.

34. Kg2 Nxb2

35. Qxb2 e4 (perhaps dreaming of a Queen)

36. Ng5 Qe7

37. Rb1 e3

38. Qb5+ Kd5 (Kings are immune from Hias)

39. Rd1 #

The Japanese Jostlers pawn is a regular Shatranj pawn (though with a different promotion). The image editor doesn't allow me to mix piece sets, unfortunately.

The piece images are not showing up on the diagram for this game

The kanji for 'Hawk' (鷹) in the piece Lion Hawk is the same as used for 'Falcon' in the Horned Falcon; while the 'Eagle' (鷲) appears in both the Soaring Eagle and the Free Eagle.

I am curious if the historical moves of the Lion Hawk and Free Eagle are not just Lion + Bishop and Queen + double-move Ferz respectively.

Could the Lion Hawk and Free Eagle instead have moved as Lion + Horned Falcon and Queen + Soaring Eagle respectively?

The Lion Hawk would be more powerful, able to move as a Lion and slide as a Queen except vertically forwards.

The Free Eagle would be slightly less powerful, moving as a Queen with the added Lion power covering two spaces each on the forward diagonals.

This could be the reference that the Free Eagle could move twice as a 'Cat Sword' (Ferz) in the Shōgi Zushiki and Sho Shōgi Zushiki, perhaps created from ambiguity in how the move is described.

I wrote a digital implementation of this a few years ago. It's somewhat incomplete and probably a bit buggy, but likely good enough to play.

Code here: https://github.com/g-rocket/trappist-1-chess/

I'm currently hosting it at http://chess.yancey.io/ -- although don't expect that to be highly available.

It strikes me as a bit inconsistent that an Ichor compulsion would not count as resolved when you push the piece onto other Ichor, while it would count as twice resolved when you push it onto a Ghast square, and then back onto the same Ichor. Of course there is a clear precedent in that you don't have to completely resolve Ghast compulsion in a single move, but there at least the severity must decrease. It would be more consistent to require all types of compulsions on the same piece to be lessened. (Which for Ichor and crowdedness would mean these have to entirely disappear.)

But perhaps this is completely moot, because players would try to avoid compelling their own pieces very strongly, even when it is not required by the rules. Still, requiring more thorough resolution of compulsion would make it easier to checkmate. I don't know if that is good or bad, though.

It's clear that the rules of compulsion as laid out here are not quite formal. I took my own stab at interpreting them on the itch.io page that I linked. To summarize my interpretation:

• Every compulsion defines conditions under which it is satisfied.
• Multiple occupancy compulsion is satisfied by moving off or destroying the piece entirely (plus some edge cases).
• Ichor compulsion is satisfied by moving off, being pushed to a non-ichorous square, or destroying the piece entirely (plus some edge cases).
• Ghast compulsion is satisfied by fleeing, being pushed further from the Ghast, destroying the Ghast, or destroying the piece (plus some edge cases).
• If it's your turn and one of your pieces is compelled, you must make a legal move that satisfies at least one of your pieces' compulsions.
• There is nothing wrong with adding new compulsions to your pieces, although this is only possible with either a Go Away's push or by a Wounded Fiend leaving a square containing another one of your pieces.

While typing this up I realized that there are a few omissions in my edge cases, which I will rectify when I get a chance. It really is tough to enumerate all the cases!

Indeed, the digestion is most conveniently indicated through changing the piece type to a visibly different one. It is no crime in chess variants to have invisible game state (e.g. castling rights in orthodox Chess), but I think this would just invite errors in the Leaf Pile case.

It is true that 'collapsing' game-theoretically identical piece types into one would affect the repetition rule. But this seems an advantage rather than a disadvantage. What would be the use of prolonging play by allowing another set of repetitions of game states that are considered artificially different (e.g. because two Mummies got swapped)? In the end repeating the sequence of moves will swap the pieces back, with the same result. In my experience pieces almost never get swapped in games without drops. (Jocly considers pieces of the same type distinguishable when testing for repetitions, in deviation of FIDE rules, and it only started to cause problems when I implemented Shogi variants.)

BTW, I am pondering about how to make a more compact description of the rules of this excellent game. A formulation that seems to go a long way would be:

Pieces can change location either by 'Moving', or by being pushed (by a Go Away). In general, Moving is only allowed to empty, unpolluted squares. But there is no restriction on squares pieces can be pushed to; the pushed pieces will coexist there with any previous occupants. Exceptions are the Zombie (which can Move to any square, and then destroys all pieces that were there before), and the Leaf Pile (which can Move to unpolluted squares containing only mobile pieces). Zombies cannot coexist with Ichor, and the two agents destroy each other. Leaf Piles digest all pieces that try to coexist with them; when two Leaf Piles meet the stationary one is digested. Removal of pieces due to failure to coexist happens automatically at the end of any turn.

About the UI issues with Go-Away pushing order: wouldn't it be a natural interface to highlight all adjacent pieces after ordering a push by clicking the Go Away twice (as already has to be done now), and then allow the user to 'click them away' one by one?

And some thoughts about compulsion:

Replacing a Ghast compulsion by a lesser one (at greater distance) was explicity declared to be legal. The other two types of compulsion do not exist in grades. (Although they could, depending on the age of the Ichor or the number of pieces in a crowded square.) It was not specified whether it was legal to replace one type of compulsion by another. E.g. when a piece is pushed from an ichorous square onto a Ghast square, is the compulsion addressed? And when the reverse happens? What if a piece gets pushed to an ichorous Ghast square? Can you resolve that by pushing it to an empty square closer to the Ghast? Or would you have to address all pre-existing compulsions on the same piece simultaneously?

I would be inclined to require that, with the exception of getting a lesser Ghast compulsion, the piece should be free of all compulsions after the move in order to count that move as legal.

The observations that certain pieces become effectively neutral in color on petrification, and that a petrified Go Away is identical to a Mummy, are almost true. However, if one were to actually make such reductions during play, information would be lost as far as counting repetitions of positions goes.

Unrelated but worth mentioning while I'm here: in my Nemoroth implementation, there are really two Leaf Pile piece types, normal and "digesting." A normal Leaf Pile becomes a digesting Leaf Pile upon engulfing a piece, and a digesting Leaf Pile reverts back to normal when it moves of its own accord (i.e. not as a result of a Go Away's scream). It's rather important to keep track of this state, or you won't remember whether the Leaf Pile is supposed to leave behind a Mummy. This is an unfortunate omission from the otherwise fine scheme in the "Nemoroth Notation" article by John Lawson -- I would suggest using a "d" prefix to indicate digestion, such as in "dL."

Some Nemoroth pieces are 'color blind': they capture or otherwise affect friendly and enemy pieces in exactly the same way. The only effect of their allegeance is then which player is allowed to move them. But when they are petrified neither player can move them, and in effect they become neutral. An alabaster and an obsidian Leaf Pile are really the same piece, from a game-theoretical point of view, and that also holds for petrified Wounded Fiends. Likewise petrified Go Aways are all the same. And since they lose their special power on petrification, they are also the same as a Mummy. And they only differ from petrified Humans when we adopt the rule that petrified Humans promote to Zombie when pushed to last rank. Which would also make it necessary to distinguish petrified Humans by color.

Petrified Basilisks remember their allegeance because of the Basilisk's asymmetric move, which is preserved in the way it sees. Ghasts have a more severe effect on foes as on friends.

W^B is referred as Manticore on CVP. An Aanca is F^R, Gryphon here. This is an old tiring discussion.

I have published this. I would recommend using P for the Pawns and another letter for the Berolina Pawns, since if this game is ever programmed for Game Courier, every piece will need to be identified by notation.

Just over twenty years after the initial publication of this page, the first ever computer implementation of Nemoroth is live, complete with a basic alpha-beta pruning AI. You can play in your browser at this link: https://azgoroth.itch.io/nemoroth

The only thing I haven't implemented is the Go Away push order, which I've been putting off due to how laborious the UI considerations are. As a placeholder, Go Away pushes are clockwise from top.

I originally wrote this implementation in TypeScript, but the AI was too slow and I ported it over to C++ using WebAssembly. I plan on open sourcing it eventually once I have more opportunities to clean up the code. This is one of the most difficult software projects I have ever worked on; I have known about Nemoroth since around 2013 but was not a strong enough of a programmer to pull it off until now.

I found a number of ambiguities in these rules, which I have tried my best to address reasonably on the linked page. Some have been covered in this comments section, some not (for example, if a Wounded Fiend leaves an already ichorated square, does the ichor stack to 11+ plies or max out at 10?).

The AI is surprisingly dangerous. It mobilizes the Ghast immediately and WILL advance it to d4/d5 if you let it, usually costing you the game. I have managed to beat it a few times, but it's tough as nails for how crude the programming is. Beware!

Ralph, if you're out there, thanks for this amazing variant. I tried to email you to get permission to make this but alas, I never heard back.

It woould be worth it to apply this in normal Shogi, to create a variant 'Impasseless Shogi'.

I was thinking the same thing with the name Impassable Shogi, or perhaps Impassable Kings Shogi to make the meaning more clear.

This is an interesting idea. It also would make kings a very large threat to each other, when they get close in ranks. Because they create an artificial board edge against which the opponent could be checkmated. Or could provide protection for a general dropped in front of the enemy king.

It woould be worth it to apply this in normal Shogi, to create a variant 'Impasseless Shogi'.

Thank you all for reviewing this rule set and for your constructive criticisms. I have been seriously contemplating the problems you have presented and your suggestions. I really appreciate your help and input as this is my first time inventing a chess variant or posting my ideas on this website. I think that it is important to respect the veteran inventors who came before me and I will do my best to acknowledge their concerns and to correct any mistakes and errors I may have made when creating this rule page.

When it comes to the names of the pieces I have chosen I didn’t realize at the time how others may be bothered that I changed the names of already well established move sets for fairy pieces. I understand that there is a long historical tradition within chess variants to keep the names of familiar fairy pieces and their move sets recognizable as to not cause confusion with other veteran players. My goal when designing ArchMage Chess was to create a chess variant that payed tribute to worlds such as Dungeons & Dragons and the Lord of the Rings universe. I wanted to make a fantasy chess game that had an element of magic implemented into it hence why I created the Mage with the ability to teleport and summon.

After some thought I decided that it would be best to rename these pieces with their more well known names from other variations. I decided that I will call the Jester a Phoenix, I will have the Griffon & Manticore instead of the Dragon & Griffon as they are named now, and the Demon & Demoness will become the Dragon King & Dragon Horse. I will call the Princess an Amazon and the Warrior Prince will become the Lion. I will rename everything besides the Mage, Sorceress, and the ArchMage as these pieces are unique and their rule sets are the focus of what makes this chess variant different from other games. As a Christian myself I understand the controversy surrounding the term “Demon Summoning” and how this would be received poorly in the west. I will change the term to “Dragon Summoning”. I know that even the Dungeons & Dragons theme, fantasy, and magic itself is controversial within the Christian community.

I will be working on adding rules explaining the situations that arise with unit swapping and promotion on the same turn as well as how the en passant rule would be affected by this.

I will consider different solutions to the summoning drop rule because I agree that as it is stated now the rule seems too powerful for actual play even with the 1 turn wait limit. It makes it so there is no great risk or severe punishment enough for losing a summoned piece if you can just easily summon it again later. This would make it so players would not value their summoned piece enough to keep it alive and may abuse it by sending it on suicide missions over and over again in order to gain an advantage. I think you all have presented really good ideas of ways to limit the power of the summoning ability. As it stands right now I like the idea that the captured summoned unit stays in the hand of the capturing player instead of returning to the hand of the original player who summoned it. This would be similar to shogi’s drop rule. The only way the player would be able to summon the captured unit again is if they have a summoner unit still in play. If the original player wanted to summon it again they would have to recapture their original unit.

I will remove diagram images that are considered excessive, repetitive, or explain rules that are already common knowledge in orthodox chess. I will simply state that the game follows the rules of orthodox chess and I will add any rules or problems that are unique to this variation of chess. For the setup description I will add the coordinate points for the starting pieces instead of just simply stating how many pieces a player starts with. I will remove the large bold headers at the beginning of each piece name as well as add a link into the pieces names directing towards the appropriate page explaining the historical fairy piece.

Thank you for taking the time to review this page.

My guess is that forbidding kings to face each other would not help. Exposed kings get checkmated very quickly in Shogi. So when the manage to cross it is always surrounded by a group of friendly pieces, from which they are chased out, and then again get new pieces dropped around the to survive.

I could imagine that the Kamikazes present the same problem as Pawns, when you are allowed to drop more than one of those in the same file.

Ever since I played a game with Greg that ended in an impasse, I felt this game may be too drawish, and I've sometimes considered changing the rules to fix this. The rule change I was thinking of was to forbid Kings from crossing to the other side of the board and to give them the ability to check each other from a distance, as in Eurasian Chess. However, it has come up that Shogi has its own rule for handling impasses, and there are alternatives to it.

The rule in Shogi is if each King has moved to the opponent's camp, which is the ranks the opponent's pieces start on, players may agree that an impasse has been reached and count pieces to determine the winner. Kings count for nothing, Rook and Bishops, promoted or not, each count 5, and other pieces each count 1. A player with less than 24 points loses. Because of the piece attrition in Kamikaze Mortal Shogi, it is possible that each side would have less than 24 points. So, instead, it could be played with the rule that whoever has more points wins. But I don't like this counting solution, and others don't too.

An alternative rule proposed for Shogi is called the Try rule. This involves winning by moving one's own King to the space the opponent's King began on. I don't know if this involves moving there only if it is safe or if it becomes a condition only after both Kings have crossed into the enemy camp. I would propose making it a winning condition only if both Kings have crossed into the opponent's camp and it moves there safely.

Similar to this is the Campmate rule, which allows a player to win by reaching the last rank with his King. I would propose the same conditions on it that I am proposing for the Try rule.

Another possibility for dealing with impasse is to reverse the directions that the opponent's pieces may move when the King moves into the opponent's camp. Additionally, pieces could be allowed to treat their own camp as a promotion zone when the opponent's King is there. These changes would discourage players from moving their Kings to the other side of the board without strictly forbidding it.

One more possibility is to allow Kings to check each other from a distance but to not forbid Kings from crossing to the other side. Instead, the ability of Kings to check each other from a distance would usually prevent both Kings from crossing to the other side, and if they happened to do so by having another piece between them on the same rank, this ability would provide an incentive for leaving the King more exposed.