
Kriegspiel - tosh
https://en.wikipedia.org/wiki/Kriegspiel_(chess)
======
thom
Over the years my friends and I have come up with some variants, with varying
degrees of fun/sanity.

1) Start with all pieces off the board. To make a move, you can either put a
piece onto your half of the board, or move an existing pieces. Captured pieces
cannot be reused (or maybe they can, if you want some sort of bughouse
variant).

2) Put a sticker under one pawn on each side. These are the 'assassins'. Be
sure to randomise your pawns without looking at their bases. During the game,
as a move, you may turn over one of your opponent's pawns - if it is the
assassin, you may choose to reveal it. If you do, you now control that piece
as if it's your colour and may move it immediately. This of course means you
have a 1/4 chance of the opposing king being in check, in which case you can
capture it and end the game right there.

3) Ghost pieces. Whenever a piece is captured, remember the square on which it
died - it now haunts this square. Any time during the game, a ghost piece may
make any capturing move from its square, but instead of capturing the opposing
piece, it merely frightens it. Frightened pieces can't move during your
opponent's next turn.

4) Tunnels! Cut out some cardboard or paper in a randomish shape to overlay
any number of squares in the middle of the board. This represents rock, into
which pieces cannot move. The first move a piece makes into the rock weakens
it. The second clears the rock out of the way (keep a pair of scissors handy).

Some of this seemed like a good idea at the time.

~~~
JadeNB
I like your (1) and (2), although (3) and (4) seem like the sort of
bookkeeping that could only be fun if you had a computer to keep track of
them.

> 1) Start with all pieces off the board. To make a move, you can either put a
> piece onto your half of the board, or move an existing pieces. Captured
> pieces cannot be reused (or maybe they can, if you want some sort of
> bughouse variant).

Can a piece be moved into any unoccupied position on your half of the board,
or only its usual starting position? Can this be done when your king is in
check (in hopes of blocking the check)?

> This of course means you have a 1/4 chance of the opposing king being in
> check, in which case you can capture it and end the game right there.

I think I don't understand this. The Wikipedia page doesn't seem to describe
the starting set-up, but I guess it's the usual one for chess. Are you
referring only to the first move? (Otherwise it seems to me that the chance of
check depends in an extremely complicated way on the game so far.) In that
case, I agree that there's a 1/4 chance of one of the pawns that could check
the king being the assassin, but you still have only a 1/2 chance of picking
that pawn correctly (even if it's there), so it seems more like a 1/8 chance
to me.

~~~
thom
You can move to any unoccupied position in your half in (1). We didn't analyse
it deeply tbh, mostly we'd just build an ultra-castle of some sort. And yes,
you can put in a new piece to block check. We didn't initially realise this,
but the king should be the first piece played, or obviously some smart alec
will just leave it off the board.

With the assassins, yes it's just a normal setup. But if your first move as
white is to turn over the black d7 or f7 pawn, and one of those is the
assassin, then you get to take the king. If they're normal pawns, you've spent
the move, setting you back in development. Probability-wise I just mean
there's a 2/8 chance that it's one of these pawns.

~~~
V-2
_" Probability-wise I just mean there's a 2/8 chance that it's one of these
pawns"_

Unless I misunderstood the concept somehow, your calculation seems to be, as
the great GM Finegold would put it, "incorrect!"

How many ways are there to pick 2 pawns out of 8? (8x7)/2, or 28. How many
ways are there to pick 2 pawns out of 6? (6x5)/2, or 15.

In other words, there are 28 combinations in total, and only 15 combinations
where NEITHER of the 2 crucial pawns is an assassin.

This means the actual probability is (28-15)/28, or 13/28, or about 46%
(rather than 25%).

Let's do a sanity check. "Safe" combinations:

    
    
        ab ac ae ag ah
        bc be bg bh
        ce cg ch
        eg eh
        gh
    

15.

"Unsafe" combinations:

    
    
        ad af
        bd bf
        cd cf
        de df dg dh
        ef
        fg fh
    

13.

Yup, math works out.

~~~
nwallin
That's not the setup. You don't have two assassins, you just have one
assassin, so it's not 8 pick 2. But there are two squares the assassin can be
on that give a move 1 mate. That gives the 2/8.

~~~
thom
Yeah this is what I’m picturing, although I’m all for creative
misinterpretations!

------
vitomd
HAND & BRAIN chess

I developed an online version of Hand and Brain Chess to play against a
computer. In each move the BRAIN (stockfish engine) will highlight the piece
or pieces that are the best move and are the only pieces that you can move. It
is your job as the HAND to play the correct move.

[http://handandbrainchess.com/](http://handandbrainchess.com/)

In the original variation 2 players plays together against someone, one say
the piece name to move (BRAIN) and the other must move it (HAND). There are
some really funny videos online
[https://www.youtube.com/watch?v=TL2pn1yIs2Y](https://www.youtube.com/watch?v=TL2pn1yIs2Y)
[https://www.youtube.com/watch?v=N-fSQAX4wkg](https://www.youtube.com/watch?v=N-fSQAX4wkg)

~~~
vadansky
At first I thought this was stupid, but after giving it a try it's addicting.
It's great to get instant feedback on a move you aren't sure about.

Edit: Is there a variant of this without limit the piece you can move?
Basically I just want the instant feedback without getting told which piece to
move.

~~~
vitomd
Yes, I also made this
[http://tacticalchess.vitomd.com/](http://tacticalchess.vitomd.com/) that it
will alert you when there is a tactical opportunity for you to win material.

Other of my projects
[http://vitomd.com/blog/projects/](http://vitomd.com/blog/projects/)

------
binarymax
You can play kriegspiel here at a site that I created and keep alive:
[http://krgspl.com](http://krgspl.com)

I built it in 2013 and am in the slow process of improving it for a relaunch
at some point.

I’m of the opinion that this game is a step up from chess, go, and poker, in
that current deep learning tech can’t be used to build a competitive engine,
due to the lack of information available.

~~~
Iv
Come, deep learning models play starcraft, a game with a much thicker fog of
war. They win at poker.

I doubt this variant would present a fundamental challenge to DL techniques.

~~~
0x8BADF00D
Hill climbing or simulated annealing would work fine, wouldn’t it? You are
constantly looking for a goal that maximizes the number of times you can
check.

~~~
binarymax
Check != Checkmate. Also you need to find the king before you can do that. And
all the other pieces that protect the king. The problem is far more
complicated than "throw this algorithm at it".

I recommend playing several games with someone else, and then rethinking your
assessment.

------
mci
_A Programming and Problem-Solving Seminar_ led by Chris Van Wyk and Donald
Knuth in 1979 was, among others, dedicated to programs playing the KRK endgame
in Kriegspiel [1].

In my previous life as a teaching assistant, I co-led a seminar that borrowed
this problem from Knuth. At the end, our students' White and Black bots played
a tournament. The feedback was: "since Black loses this endgame sooner or
later, those who developed bots playing White had more fun". Next year, we
came up with a symmetric game.

[1]
[http://infolab.stanford.edu/pub/cstr/reports/cs/tr/79/707/CS...](http://infolab.stanford.edu/pub/cstr/reports/cs/tr/79/707/CS-
TR-79-707.pdf#page=69)

------
chess93
"In the game of chess, you can never let your adversary see your pieces." \-
Zapp Brannigan

I, for one, would love to see professional players attempt to play this game.
It does seem extremely frustrating to play, however.

~~~
iamnotacrook
Blindfold chess? Just search for it on youtube. Most GMs can do this easily.
Some simultaneously play 10+ sighted players whilst blindfold. Even when not
blindfolded they often look away from the board whilst calculating so that the
current state of the board doesn't distract them.

~~~
busyant
It's not exactly blindfold. With blindfold, the blind player still knows the
opponent's moves...They just don't have the luxury of being able to _look_ at
the state of the board (although top-tier chess players don't need that
luxury).

This is a little different, but I think/speculate they would still have enough
heuristic knowledge to crush most people.

------
onnodigcomplex
Suckerpinch (Tom) recently had a video[1] about predicting the position of the
oponents pieces from knowning just white. I don't think he's aware of this.
Great video anyway.

He trained an NN to predict the pieces and then used Stockfish on the
resulting position.

[1]
[https://www.youtube.com/watch?v=DpXy041BIlA](https://www.youtube.com/watch?v=DpXy041BIlA)

~~~
NoodleIncident
Yeah, the "pawn tries" rule in particular reminded me a lot of his "blind
spycheck" algorithm in that video. If you are allowed to rank every move and
perform the first legal one, you can get away with some interesting stuff.

------
mih
Interesting. This reminds me of how a history teacher used a variant of Chess
to simulate warfare as part of a class project -
[https://www.reddit.com/r/occupywallstreet/comments/13gemx/so...](https://www.reddit.com/r/occupywallstreet/comments/13gemx/social_conflict/c73rvo4/)

~~~
jbattle
That's an amazing story, I'd have loved that as a kid (or now!)

------
rrauenza
I had just looked up this wiki article a couple days ago based on this video:

[https://youtu.be/DpXy041BIlA](https://youtu.be/DpXy041BIlA), "30 Weird Chess
Algorithms: Elo World"

 _An intricate and lengthy account of several different computer chess topics
from my SIGBOVIK 2019 papers. We conduct a tournament of fools with a pile of
different weird chess algorithms, ostensibly to quantify how well my other
weird program to play color- and piece-blind chess performs. On the way we
"learn" about mirrors, arithmetic encoding, perversions of game tree search,
spicy oils, and hats._

Is this also why it showed up just now?

------
mcguire
Infochess "is a chess variant designed to simulate the relationship between
what is known and what remains unknown in conflict, and to stimulate a deeper
appreciation of the interaction between the informational domain and more
traditional military affairs." It includes abstracted psyops and electronic
warfare.

[https://calhoun.nps.edu/handle/10945/48155](https://calhoun.nps.edu/handle/10945/48155)

------
manjana
Those interested in chess game variants should also check out www.lichess.org
or LiChess from Google Play

From Wikipedia article describing features of the platform:

> In addition to enabling blindfold chess,[18] the website supports the
> following chess variants:[19]

Antichess (Losing chess)

Atomic chess[20]

Chess960 (Fischer Random Chess)

Crazyhouse [21]

Horde (a variant of Dunsany's chess)

King of the Hill

Racing Kings

Three-check chess

~~~
binarymax
Having played a number of those, IMO they are nothing like Kriegspiel, which
is in another category. I grew up playing chess and at our club and we also
played many variants. Kriegspiel was a whole other monster that we would play
in teams, one group sitting in on room, and the other next door so you had to
whisper and show experiment moves quietly in the group. The arbiter would
register on a central board and announce. The experience is difficult to
recreate on the web, and I know Lichess hasn’t added Kriegspiel to their
variants list even after several requests to do so.

~~~
alecmg
Why is Kriegspiel difficult to do on web?

As I was reading the description, I immediately felt that a online version of
it would be much simpler and quicker to play than real world version. No need
for umpire and multiple boards (handled by game server), all the announcements
could be automatic and visual, immediate feedback on blocked moves etc.

~~~
Swenrekcah
From their description it seems like the social aspect of it was a huge part
of the experience

~~~
binarymax
Yes, it is! You cannot allow games-in-progress to be viewed (to prevent
cheating). So how can you allow a team to be all viewing the same side of the
board and prevent spies? I haven't figured out that solution yet.

------
FrojoS
What about scouting? You could have a rule, that you are informed about the
pieces in the vicinity. Perhaps even have different view distance for
different pieces. Or only reveal the existence but not the type of a piece for
longer distances and then type when closer.

~~~
falcor84
One of the See Also links in this article is just this:
[https://en.wikipedia.org/wiki/Dark_chess](https://en.wikipedia.org/wiki/Dark_chess)

------
flamtap
One of the rules made me chuckle:

> "No", when the attempted move is illegal, given the opponent's position.
> [...]

>"Hell no" (or "Impossible"), when the attempted move is always illegal
regardless of the opponent's position. [...]

------
bravura
I invented a similar chess variant that doesn't require a referee.

All the pieces are one color, but on the bottom of the pieces you mark the
true color (black or white).

When it's your turn, you can either move, or challenge your opponent that
their last move was false. If you challenge, they turn over the piece they
just moved. If it was their color, you lose your turn. If it was your color,
they move the piece back and you get to move.

Don't even get me started on Go Chess, a hybrid of Go and Chess played on a
chess board with both Go and Chess pieces, where in the Go world even Chess
pieces are treated as Go pieces.

~~~
dmurray
So with a small bit of short term memory this is equivalent to chess? That's
not really a similar variant to the hidden-information game that is
Kriegspiel.

------
brbrodude
If this seems like random shit rules to you, make sure to check out this
amazing video about Kriegsspiel:
[https://www.youtube.com/watch?v=-seIA9tukDs](https://www.youtube.com/watch?v=-seIA9tukDs)

Seriously awesome information based system design way before computers, it
seems like such an advanced game/simulator. One of the things I'm most
interested in is how sophisticated past humans could get with their tech &
circunstances they had at their time, this is one of those to me.

------
bytematic
_" 'Hell no' (or "Impossible"), when the attempted move is always illegal
regardless of the opponent's position. For example, moving a bishop as if it
were a knight."_

Amazing.

~~~
human20190310
It would be cool if there were a variant of this variant where one also had to
discover 1) what the legal moves were, and 2) whether there is an opponent
there at all.

------
thinkingemote
Not related to the equally fascinating Kriegspiel war game created by
Situationist Guy Debord

"In Debord's view the game represents the totality of factors at play in
wartime maneuvers, what he called "the dialectic of all conflicts."

[http://r-s-g.org/kriegspiel/about.php](http://r-s-g.org/kriegspiel/about.php)

~~~
mcguire
Weird. The only other time I've heard of Debord or his game was two chapters
in _Zones of Control_.

------
justintoon
Zach Gage created a version where both sides get a random assortment of
pieces, which certainly turns the game on its head.
[http://reallybadchess.com/](http://reallybadchess.com/)

------
michal_sustr
We have research lab at CTU in Prague where our focus is on imperfect-
information games. We are working on scaling up algorithms that have worked
well in Poker, and extend them to other domains as well. Poker has some nice
properties - the hidden information (player's private cards) does not change
through the course of the game so the value functions needed for neural
networks can be computed "nicely", as they have fixed input/output sizes.

We definitely see Kriegspiel as one of the next challenges.

AMA if you're interested :)

------
billfruit
In my thinking, if there was some RNG added to the turn by turn play of chess,
with means of improving the odds through tactical play, then it would be the
perfect 2 player board game.

Otherwise, it's almost impossible to fight back and win a chess match through
audacious, if risky play, in normal chess. Once a person is in a position of
advantage, they almost always win, unlike say in backgammon, where the player
at disadvantage can deny victory to the other, for sometime, during which they
might figure out some striking counterplay.

~~~
dragonwriter
There are a number of games which amount to some random element added to
standard chess, one example is Knightmare chess:
[http://www.sjgames.com/knightmare/](http://www.sjgames.com/knightmare/)

I seem to remember a simpler variation involving rolling dice to determine
what pieces are allowed to move, but I can't seem to find anything about it.

------
dooglius
In the rules I used to play by at chess camp, you had to ask "are there any
pawn captures", and if there were, you had to make one--this removes the
additional information issue.

------
roasm
My daughter invented one version with regenerating pawns. I play regular chess
on my side, and on her side, she has the king, queen, and 8 pawns. On her
turn, she can choose to move a piece as normal or put a pawn on any square on
her half, but only if she's had a pawn captured (so off the board).

It creates a strange desire for her to get her pawns captured so she can plop
it down somewhere else, and a strange desire for me not to capture any pawns.

~~~
thom
Sounds like you might enjoy teaming up in bughouse!

[https://en.wikipedia.org/wiki/Bughouse_chess](https://en.wikipedia.org/wiki/Bughouse_chess)

------
pflenker
There is not much that I remember from 5th grade, but what I do remember is
that after half a year of teaching us chess during Chess Club, our teacher has
beaten all of us simultaniously while facing the wall and announcing his moves
after we announced ours.

It's rare to see that much expertise and skill in action.

~~~
tudelo
Maybe you learned the wrong moves ;)

~~~
pflenker
Oh, I am very bad at Chess. Still, beating around 10 kids at the same time
while facing a brick wall was very impressive.

------
derefr
Is AI as good at Kriegspiel as it is at regular chess?

Is there a Go equivalent? If so, is AI any good at that?

And, if either answer is _no_ : then why did DeepMind go straight to trying to
solve a game that was both incomplete-information _and_ realtime (Starcraft)
instead of merely incomplete-information (Kriegspiel)?

~~~
dmurray
Kriegspiel is a very niche game. There are no professional players and it's
not clear what it would mean to achieve superhuman performance.

At one point Stratego was the standard for incomplete-information (but non-
random) games in AI research. That may no longer be considered challenging,
but either way, crushing an AI tournament in that wouldn't attract the level
of publicity DeepMind get from chess, go or Starcraft.

~~~
moccachino
On an _extremely_ tangential note: If you need some fun, short shows to relax,
watch White Gold on Netflix. Stratego plays a small part in the second series.

------
Balgair
Invicta on Youtube has a good historical overview of the 'actual' kreigspiel
game:
[https://www.youtube.com/watch?v=-seIA9tukDs](https://www.youtube.com/watch?v=-seIA9tukDs)

------
hestipod
Nein danke. I cannot envision the "future board" well enough to play NORMAL
chess very effectively. I cannot imagine not being able to see the enemy
pieces at all.

------
TuringNYC
Thanks for sharing. The whole time reading this, I was thinking how
straightforward it would be to re-factor online/electronic chess games to also
support a Kriegspiel mode. I'm surprised I have not seen the option.

~~~
komaromy
ICC used to have it (probably still does)

------
C1sc0cat
(chess) needs adding here

------
JohnJamesRambo
You sunk my battleship.

------
Avalaxy
What I don't get about hackernews is why regularly someone just dumps a link
to a random wikipedia article with no context of why it's here and why it
should be interesting. Can we just change this and add some context?

~~~
justintoon
Maybe to spark conversation?

