The definitive list of the most popular and/or respected variants

[ghost]

The variants below are listed in no particular order. I won't list the rules here, only remark on variations upon them and the technical challenge of implementing them.

Probably doable right now:

1. Extinction Chess -- one of the most popular variants.
2. Patrol Chess -- sometimes used as an educational tool and also appreciated by higher-rated players.
3. Grid Chess -- featured many times in magazines of the past when they talked about interesting variants. It was apparently the benchmark to compare new variants to, due to its age. It is still popular today.
4. Rifle Chess (AKA Shoot Chess). Most often played with mandatory captures, as the page notes. Not sure how possible it is to simply remove untouched pieces, though.
5. Kriegspiel and the somewhat computer strategy game-like Dark Chess (which has a fog of war mechanic). The core element of these variants is deduction, combined of course with good chess play. As per previous discussions, these variants are probably some of the lowest in priority. It would be difficult to prevent cheating in them (unless there is a way to have games as fully private) and they utterly lack the element of spectacle. Requires a complex referee-ing system. Both are extremely well known and widely played; many masters have played it and continue to play it.

Probably not doable right now:

1. Bughouse Chess -- easily the most popular (after 960) of all variants at club level and beyond. Same issues as the above, but with two more players -- which pushes it much further from implementability. Encoded in the BPGN format.
2. Alice Chess -- a very peculiar variant that is endemically popular at all levels. Same implementation issues as Bughouse (though it's played between 2 players, not 4).
3. Capablanca Chess -- very popular variant that has always been appreciated at high ratings. Popularity continues into today, though some reckon it is dated and has design flaws corrected by later variants partly inspired by it (esp. Grand and Omega Chess). Grand Chess is also worth a look when it comes to this variant. Many masters prefer one or the other and see them as two sides of the same coin -- but many think they're different enough variants in their own right. Both are extremely respected nonetheless. Both add fairy pieces and have larger boards, making them impossible to implement right now. Also see Gothic Chess [full rules] which changes the starting position.
4. Marsellais / Progressive / Doublemove chess. These really ARE two (or three) sides of the same coin. Not doable due to one side being able to make more than one move at a time.
5. Glinski's Hexagonal Chess. Not implementable for self-explanatory reasons. This was a hugely popular variant in the past, believe it or not. Just keep in mind that there are many hexagonal variants, but this is the one that's usually referred to when someone says 'hexagonal chess'.
6. Ultima (AKA Baroque chess) -- very peculiar variant but extremely well-known and played since its inception. Piece movement is just one of the many reasons this is not possible with.
7. Omega chess -- possibly not doable due to copyright reasons. Very popular variant; one of the few commercial variants that have been very successful with high-rated players and are also still in print today (!). Not doable due to the larger board and new pieces.
8. Avalance chess. You move your opponent's pawn after each move you make. Basically means that each player makes two moves. Unihedron knows a variation where you move your opponents' pawn to the opposite of the square your piece / pawn landed, if it's a legal move -- worth trying. Refusal chess, a favourite of Vinvin, is related but can well stand on its own right.
9. Magnetic / Dynamo chess. Magnetic is almost certainly the more popular of the two, and also the more complex. Have a similar mechanic but some differences that cause very different play. Very well respected and popular variants indeed, but not doable due to strange movement mechanics.
10. Unachess -- very popular variant which actually had a feature request in lichess forum recently. possibly doable now is a bit of a stretch, though I suppose you could do it with a shared board editor or something of the sort.
11. Four-player chess
12. Musketeer chess

NB: many of these variants were popular in the pre-internet chess era but were underserved by programmers, so they never got a chance to be as popular as they once were. Also note the list was made intentionally so it reduces replication of features/themes between variants (so there's only one Shogi-like variant, Crazyhouse, instead of having Chessgi and a bunch of others). I looked solely at others appreciationg

[ornicar]

:+1: that's gonna be very useful

[rwill128]

Thanks for doing this! I just discovered lichess but I'm looking forward to contributing.

[ddugovic]

Very nice! I do enjoy a few other variants:

1. Thematic chess - start from a thematic (opening) position, but otherwise is standard chess
2. Wild5 - start with pawns on the 7th rank, pieces on the 8th rank
3. Billiards chess - pieces can carom off the board edge!
4. Cylinder chess - chess played on an 8x8 cylinder (a-file and h-file adjacent)
5. (name forgotten) - game starts with an extra piece on the board which moves the same direction and number of squares as the moved piece, cannot capture, and cannot be taken
6. Soccer chess - although I've never seen a rule set for playing this on an 8x8 board!

[ghost]

Thanks for the response @ddugovic.

The first two are already covered from the board editor and are not particularly popular. However, thematic chess tournaments have been considered if I remember right. EDIT: thematic tournaments have now been implemented.

Wild 5 is also easily possible with the board editor, and frankly, does not get a lot of respect. It's also somewhat solved. I don't think people would flock to play it.

Billiards is quite obscure, though definitely a cool variant.

Cylinder chess! I thought about including this, but that would be going a little overboard, because this is ultimately still a lichess list. Definitely one of the more well-known variants, but it really needs that cylindrical shape to work. There is one more condition to being listed here which I didn't state, but basically, you should be able to represent all the variants on a 2D plane. Sadly, cylindrical chess does not fit that criteria. :/

Can't say I've heard of number 5 before.

I admit, I forgot football chess. ;) Though I need to find what the most popular set of rules for it is, because there are a lot of variants that try to make chess emulate the rules of football. Don't worry about board size, this is a list of the most popular variants regardless of how they function or play. Not being 8x8 simply means it gets put under the 'Probably not doable' category.

[ddugovic]

Regarding Football Chess, I recommend that the "official" rules are Boyer's 1951 rules (rather than Neto's 1997 rules which would be much more difficult to implement).

That said, a few rule changes could adapt those rules to an 8x8 board:

1. The game is played on an 8x8 board, with the ball starting on a random center square.
2. Goals are located at (d1 + e1) and (d8 + e8) & may not be occupied by pieces. Goal posts are on the perimeter of these squares.
3. Therefore the starting position is with the king and queen on the 2nd (7th) rank; or possibly all pieces on that rank (no castling).

[Unihedro]

Random is bad.

[ghost]

@ddugovic there is no limit on board size, this is pretty much the 'crazy ideas' issue.

Knowing that, are you still confident in the alterations you proposed?

[ddugovic]

@Unihedro OK; in that case, I recommend the ball start on e5 (White goes first, the ball is closer to Black).

@Evropi I think my intuition is correct although I'm not 100% confident in specific details. I believe that 1x1 goals on a 8x8 or 9x9 board are too easy to guard, and that since the start position lacks pawns (increasing mobility of long-range pieces) it makes sense to either bring the knights closer to the center, or have the Q and K initially blocking the Bs.

I prefer the simplicity (ease of understanding) of Neto's Rule 3 (how to kick the ball):

To kick the ball, a piece must go to the ball's square (possess it), then move it to any square where that piece could move to.

and I think Boyer's rules could be made easier to understand if a "pass" consisted of kicking the ball to a square occupied by a friendly (or opposing?) piece! So basically, a player's turn consists of:

1. Move a piece (unless either player possesses the ball)
2. Kick the ball (if in possession of the ball)

[ddugovic]

I can hardly believe I omitted one of my favorite variants: Laser Chess! Pew pew pew!

Each player has a laser. On a player's turn, they may:

1. Rotate a single piece 90, 180, or 270 degrees
2. Move a piece (the laser moves like a king) or fire their laser

Lasers destroy pieces except when they are absorbed (pawn shields), reflected (most pieces), split (bishops), or "phased out" (queen) protected the queen and the square immediately behind it.

[ddugovic]

ZugAddict and I invented a variant of a variant: Relay Chess! Rules follow:

1. Pieces (including the king; not pawns) gain movement abilities from friendly pieces which defend them. For example, a knight defended by a pawn may move as if it were a pawn; a queen defended by a knight may move as if it were a knight; an unmoved queen defended by a king may castle (with an unmoved rook)!
2. Kings may never move through check.
3. A piece (excluding the king) on a player's 7th rank defended by a pawn inherits the pawn's ability to promote if moving like a pawn.
4. En passant is legal if the opposing piece advanced two squares because it moved like a pawn (not because it moved like a queen or rook). For example, 1. Nf3 e5 2. Nf5 exf4ep is legal, but 1. e3 e6 2. Nf3 e5 3. Nf5 exf4 is illegal.

Example game: http://www.twitch.tv/zugaddict/v/24530100 (Actually, in this game Rule 3 was never relevant, and I don't know whether Rule 2 is a good idea. EDIT: I'm warming to the idea, especially since it's consistent with Rule 1.)

Notation: queenside castling is always denoted O-O-O; kingside castling is always denoted O-O. Queen castling moves are indicated by the player moving the queen atop the rook to castle with, causing the Q to move sideways two squares and the rook to move to the other side.

[ornicar]

I'm giving relay chess a try, excluding rules 3 and 4.

[ornicar]

yeah nah, scalachess makes too many asumptions about the way pieces move, for perf reasons. It's not flexible enough for relay chess.

[AndrewNg]

@Evropi could you elaborate a bit on the technical difficulty behind dropping in pieces? If I recall correctly one of the main reasons why people play on FICS is for the bughouse community. Bringing bug to Lichess would great for growth as it's by far the most popular variant.

[ornicar]

It cannot be encoded as PGN, which is lichess de-facto storage format.

[AndrewNg]

Is it out of the question to use a format like BPGN? I believe that's the standard that FICS and ICC use for storing Bughouse games. Granted, planning out the UI for playing and replaying bughouse games will be extremely difficult, but the logic for gameplay and storage seems straightforward.

Of course, if parts of Lichess are heavily dependent on PGN then I can see why this wouldn't be possible.

[Unihedro]

Suppose a deriverative of PGN like BPGN is adapted when implementing a new variant. What do we do when we need another PGN construct? invent R-BPGN?

Changing to different standards with no replacements isn't a scalable approach and simply doesn't work.

[Egroegw]

I know that Evropi has said that Dark Chess is probably not going to be implementable in the near future, but he also predicted Crazyhouse Chess would be near-impossible to implement. Now that Lichess includes Crazyhouse, I would like to suggest that Dark Chess be also considered.

Essential rules: The aim of the game is to simply capture the enemy king, and all rules regarding check (and their implications on castling and pins) are suspended. Squares on the board to which a player cannot move a piece next move or do not contain a friendly piece are unknown, and he/she is not shown whether it is empty or it contains an enemy piece. Squares diagonally in front of pawns are always known.

More explicit rules can be found in many places, among which is Wikipedia: https://en.wikipedia.org/wiki/Dark_chess.

Potential Implications

• Games will have to be private (no spectators) until they are finished in order to prevent cheating. This was something Evropi mentioned, and is logical.
• Moves an opponent makes during a game would need to be either obscured or hidden on the move-list.
• Rules for showing unknown squares would need to be worked out, and is probably the hardest part of implementing Dark Chess.

The following are some drawings I made in envisioning what the board could potentially look like during and after a game:

[Unihedro]

On "Implications", I think if a game of Dark Chess is not rated, it may be OK to allow spectators.

[aurimus]

Kung fu chess anyone? .. Bullet players should love that

[Unihedro]

Bots would love it even more.

[aurimus]

Love the idea of variants here, especially the "Spy-chess": http://en.lichess.org/forum/general-chess-discussion/secret-queen---new-variant?page=2#18

[CastleII]

I'd like to add a new variant of Crazyhouse with the intention of make Crazyhouse more similar to Chess, this means making a much more strategic game, but at the same time maintain a very high level in the tactical part, this would be achieved adding three rules governing how the drops are made:

• Rule 1: A drop move with a check is illegal
• Rule 2: Pieces (not pawns) can only be dropped from first rank to seventh rank
• Rule 3: Pawns can only be dropped from second rank to sixth rank

I played a lot of blitz games of this new variant vs Sjeng, a Crazyhouse engine, these games may illustrate what I try to mean with a much more strategic game, I imported some games in my lichess profile: http://lichess.org/@/castleII/import

One example position showing how to checkmate in Crazyhouse as well as new [Strategic] Crazyhouse:

In traditional Crazyhouse there are 2 mates in 2 moves: 1. Q@e8+ Bxe8 2. Rxe8# 1. Re8+ Bxe8 2. @e7#

In new [Strategic] Crazyhouse there is mate in 5 moves: 1. Q@g7 N@g6 2. Qxf7 Q@c6 3. Re8+ Bxe8 4. Bxc7+ Qxc7 5. Qxe8#

Replay game here: http://lichess.org/bEPq7oOW#72

[Unihedro]

There are too few differences from Crazyhouse to make it its own variant and give it its own icon and rating tracker. It can already be played as-is, with the addition of house rules.

[CastleII]

Yep, these are a few differences but have a huge impact on the game strategy, anyway I agree that for now maybe there is no need to add this as a new variant, but at least it is necessary to add an option that allows the control of these rules, otherwise players can make a lot of illegals moves by mistake in rapid games.

An example of a possible control would be a button inside the game:

[nicoguaro]

I think that Cylinder chess can be implemented in the 8 x 8 board. You can define the diagonal movements as modulo 8, with the reminder of the division as x % 8, no?

[abeswick]

Please please please could you add Alice chess to Lichess.org? I'm sure it would be possible to implement this, there must be a way you could flip between the two alternate boards (might be better than seeing them both on the same screen due to the size issues). In reality when you play the game you can only look at one board at a time anyway and I think the idea of the game is to help with visualisation anyway. Another option would be to have a single board with the second board pieces marked, however I think the first options is much better as you shouldn't be able to see both boards together anyway. I think it is a great game for creativity and visualisation skills.

Also have a few other requests though that is the main one:

Blindfold chess - I know you can play in blindfold mode but you should be able to select this as a game type and have a rating too. The reason being that the opponent should also be playing blindfold, the other thing is that you should not be able to see the board at all (even if it's blank), just a screen with coordinates (or be able to choose this anyway.

Also some of the other variants by V. R. Parton would be nice, in particular: Gryphon Chess, Synchronistic Chess, Identific (all on the wikipedia page). Flying chess would also be nice.

Thanks :)

[abeswick]

Sorry, one other idea I had was to add the feature to standard chess to play without a piece and a move etc, as they did in morphy's games. I think it would be an interesting way to level out strength, also playing with different time limits for each opponent might be an option too.

[gbtami]

https://en.wikipedia.org/wiki/Makruk "There are around two million Thais who can play makruk, while 5000 can play chess."

[enfor450]

Power Chess would be easy. The hard part would be choosing which piece: Apart from the king and pawns, all pieces are queens, or bishops, or knights, etc. All other rules are the same as chess, except pawn promotion would be only to the piece in the game. (you cannot promote to a rook in a Knight game) I invented this variant, and have not created a website yet, but I'm sure that lichess could implement it! [EDIT]: Knights might be a favorite, especially with the famous Chess-Network quote: "Watch out for the tricky knights"!

[Vinvin20]

"There are around two million Thais who can play makruk, while 5000 can play chess."

I agree to open Lichess to eastern games.

After all, half of the humanity lives in this circle : https://pp.vk.me/c7010/c614917/v614917201/927c/NW0QoNgJw6A.jpg