Chicago Bulls:The program(Scid) has nice graphics for itself. I was lazy so didn't upload them or didn't modify the produced file to do your suggested trick. It's the normal start position.

chess database programs does a fine enough job with ambiguous chess

Oh OK. And one note: The pieces from the site http://h1.ripway.com/sanjaab/bitmaps/ do not appear at all, so in the page you provided for Ambiguous Chess statistics i can't see a board with pieces. I suggest you to put the pieces from the following site(do not click it as nothing will happen):
http://www.marochess.de/php/chesspieces/

And you can choose the desired piece to include in your code for the board position with the following way:
After http://www.marochess.de/php/chesspieces/
put CPn.gif
With:
C = W or B for white or black color piece
P = Q or K or R or B or N or P for Queen or King or Rook or Bishop or Knight or Pawn.
n = a number from 1 to 8 for each piece set that matches your size of the board. Of course if you use 1 for example for black rook then you will have to use n=1 for all other pieces too.....
n=1 is a good choice by the way.....

For example http://www.marochess.de/php/chesspieces/WQ1.gif produces the image of the white Queen from set 1.

Chicago Bulls: Sorry, it's generated by a filter to just include the games of 10 current top rated(provisional or stablished) ambigous chess players on this site.
just 159 games and 51 are nabla's games

And where exactly are the top 10 Ambiguous players in that page? LOL!

For statistics lovers:

Top 10 ambiguous players

All

Chicago Bulls: OK I understand, I suppose that this has be done for chess openings database, but I had never seen it before. Now, it seems clear that it requires a great number of high-level games, and I don't think that we have either of these in Ambiguous Chess yet.

nabla:
It's simple:
Take for example the line after After 1.d4 d5:
2.c4 games played = 30, Percentage wins = 93%
2.f4 games played = 6, Percentage wins = 50%

It is not clear at all that 2.c4 is the better move here. You will say but why? It has won for white in the 93% of the games! A huge difference over 2.f4 that wins on only 50%. But this may be completely deceiving.

Consider for example that after 2.c4 and for simplicity's sake, that there are 2 responses to this:
2...X1 that has been played 26 times with a devastating score of 95% in favour of white and 2...X2 that has been played 4 times with a bad score for white of 25%.
2...X1 was the move all people played some time ago, until the new move 2...X2 discovered and been played with a good success for black.
That means we possibly have a refutation to 2.c4 since 2...X2 brings good results for black! Although statistics say 2.c4 has a good %, since many games were played with the bad response for black 2...X1.

The bad thing is the refutation may be deep in the openings-data tree or there may be another refutation to the 2...X2 move later in the tree so 2.c4 is good after all! To solve all these a complete examination of the whole opening-tree should be done starting from the leaves of the tree and going up all the time until we end to the starting opening moves. In that way going backwards(that's the meaning of backsolving) we find the best value(+-,-+, ++-, --+,etc) of each node.....

nabla: Myabe something like BKR averange of players who used this move and their performance BKR. If you look these too you could at least tell something.

Chicago Bulls: Thank you for this work !
What is backsolving ? How would it tell which moves are better ?

Note that these statistics should not confuse us about what is better to play or not. I mean that after 1.d4 d5 for example, when we see 2.c4 with a win=93% while with 2.f4 with a win=50%, we should not been deceived and believe that 2.c4 is much better or even better! This may not be the case! In order to know for sure a backsolving procedure should be done.... But i don't have right now time for this. Later....

nabla: .
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Yes unfortunately i didn't know that when i downloaded all the Ambiguous Chess games those currently played was included too....But after a clearance and a re-generation we have these:

For example:
After 1.e4
1...e5 Win%=44 means that black has a score of 44% against white when he plays 1...e5

Starting move
Move Games Win%
1.e4      321      45
1.d4      114     61
1.f4         70     53
1.c4        66     64

After 1.e4
Move Games Win%
1...e5    125      42
1...c5     74       66
1...d5     49      71
1...e6     36      62

After 1.d4
Move Games Win%
1...d5     61      31
1...e6    17       55
1...f5     13       61
1...c5      9       50

After 1.e4 e5
Move Games Win%
2.c4       24       70
2.d4      23        63
2.Qh5   17        58
2.c3      13        38


After 1.e4 c5
Move Games Win%
2.Bb5     15       60
2.c4        10      40
2.d4         6       33
2.b3         6       16
2.c3         6         8

After 1.e4 d5
Move Games Win%
2.exd5    25       24
2.e5         8        75

After 1.e4 e6
Move Games Win%
2.d4      22        36
2.c3       5         40


After 1.d4 d5
Move Games Win%
2.c4      30       93
2.f4        6        50
2.e4       5        60
2.g3       5        40

After 1.d4 f5
Move Games Win%
2.c4        6        33
2.Bg5      2        50


After 1.d4 e6
Move Games Win%
2.e4         7        42
2.Nc3      3        50
2.g3         3        33

Chicago Bulls: That is very nice, good job ! But the numbers make me suspect that you counted unfinished games as draws, because at the moment I write this message the counters show only 726 finished games.

For example:
After 1.e4
1...e5 Win%=44 means that black has a score of 44% against white when he plays 1...e5




Starting move
Move  Games Win%
1.e4       634       47
1.d4       245       56
1.c4       144       58
1.f4        131       56


After 1.e4
Move   Games Win%
1...e5     255      44
1...c5     140      61
1...d5      85       65
1...e6      64       60

After 1.d4
Move   Games Win%
1...d5      123      36
1...f5         34      66
1...e6        31      54
1...c5       17       47


After 1.e4 e5
Move   Games Win%
2.c4         50      66
2.d4        43       55
2.Qh5     30       60
2.c3        30       46


After 1.e4 c5
Move   Games Win%
2.Bb5     22        54
2.c4        21       40
2.d4       15        43
2.c3       12        25

After 1.e4 d5
Move   Games Win%
2.exd5     42        32
2.e5        14         64

After 1.e4 e6
Move   Games Win%
2.d4          34         36
2.c3            7         42


After 1.d4 d5
Move   Games Win%
2.c4         59         79
2.f4          11        45
2.e4           9        61

After 1.d4 f5
Move   Games Win%
2.c4         16        31
2.Bg5        6        41

Chicago Bulls: It's not different at all, in fact why would anyone consider exd5???, it loses the game immediately. Why allow stupid mistakes?

Chicago Bulls: I fully agree that my first suggested option would make the game less interesting because defence would superseed attack.

Chicago Bulls: In your example, grenv would probably like 8.exd5 to be rejected by the system as illegal.

grenv: So you say that in Atomic Chess 8.exd5 should not be allowed for white or even worse 8...Qxd2 with win, should not be allowed for black?

1. Nf3 f6 2. Nd4 Nh6 3. f3 c6 4. e3 d5 5. Nb5 cxb5 6. Bb5 Nc6 7. e4 Ng4 8.exd5 Qxd2 0-1

But that would just be another variation of Atomic Chess different than that we have here.....

grenv: If my question wasn't, your answer was very clear :-)
Making moves that leave the king in check illegal is indeed an alternative formulation in my personal ruleset ( http://www.pion.ch/echecs/variante.php?jeu=ambigus&rubrique=regles&changer_langue=E ) . Basically it doesn't change the game at all (except for the stalemate, but I like the fact that stalemate is a win), has the advantage to cut off silly mistakes, to make the game more chess-like, but the disadvantages to make the rules more difficult to understand, three times as long and more difficult to implement.
The last reason is enough to make any programer prefer the simple no-check no-mate formulation, and even if I supported your proposition, I am sure that Fencer would not. He didn't implement checks in either Atomic Chess or Extinction Chess, and rightly so imho.

nabla: In the first case the game would be inferior i think, while in the second it's pointless since it's just a delay of the loss....

nabla: I didn't really understand your question, but what I meant was that moves leaving the king in check should be illegal.

Atomic chess should be the same, except that "check" should mean any situation where I can blow up the king.

e.g.
1.Nf3 f6
2.Ne5+

or
1.Nf3 a6
2.Ne5x

grenv: That is something that could be said about Atomic Chess by someone playing his first game, giving an orthodox check, and seeing his opponent answering by ignoring the check and blowing his king up !
Did you mean that one should disallow to choose a move leaving the opponent in check, or only redefine "checks" so as to avoid that a player can lose his king in one move (that is, making those moves illegal instead of losing) ?

grenv: I do not see the point neither why check and mate do not exist.

grenv: Knight Relay Chess is the game!

I played ambiguous chess a few times, and I have to say i think introducing check would make it a better game. Either way it's pretty silly.

sewzay: It should be a draw, but I think the players would have to agree, i don't think it's automatic.

In Atomic Chess, if both players are reduced to their kings is the game declared a draw, or can there be a winner?

I'm asking as the king is not allowed to take pieces as it will blow itself up.

That piece is the same which I have heard called elephant in african chess. It is said to be better than queen, but I am not sure if it is really better than Maharajah. Maharajah can go all the same squares, unless it is blocked. Maybe mix of these pieces would be better. Maybe we could call it Elephant Mounted Maharajah,

tbart: Perhaps the Maharajah could be replaced with Chu Shogi's Lion? It can only move one or two squares, but its capturing power is pretty strong. It'd be a real challenge to trap a Lion instead of the methodical way the Maharajah can be tracked down by anyone that knows what they're doing with the Chess set pieces. Hmm, maybe it'd be too strong? It'd be worth a try anyways.

an idea to balance maharajah: take away 2 black rooks.
an idea to balance horde:give black 2 free moves. I feel that whites advantage is not as big as the stats say it is. a good black player will try to keep the posistion closed and put up a battle.

Beren the 32nd: Oh I see now ... yes amazing ...

Beren the 32nd: .
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Exactly! Amazing huh....?

WhisperzQ: I think that white will choose the Knight to take the Knight on d5 and then give 'check' with the Bishop. Surprisingly, the King cannot avoid capture now!

nabla: Okay, I give in, why can't black now click on d5 so that the knight is taken (presumably by the queen which in turn gets taken) ... but then there is no mate (or Kingtaking) is there?

Harassed: Actually it was a nice "king capture in 4", which is analogous to a mate in 3. However, I didn't see it coming at all, probably disregarding the possibility that White would not choose the capture on d5 to be made by the black queen.

mangue: .
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my most beautifoul sacrifice :

Oh holly crap! Many thanks for this!!!!
Although i haven't yet started to investigate the game but with this sacrifice, my brain has built many patterns so it help me a lot....
Now i should observe many more games to help my brain understand what is going on. Please if you have any new brilliancy post it.... And not only you....

WhisperzQ: This is 99.9% correct. The only difference is that Fencer did it (rightly) so that when more than one piece can take the king, selecting the king's square as destination wins the game outright, the opponent does not have to choose who will eat his king.

plaintiger: Questions about rules do not bug me ! Although you already got the answer, I would add that in any chess variant saying "no check or checkmate, the goal is to take the king", it must be understood as "you are allowed to leave your king open to capture, though you will lose the game if you do so".
Actually, you can still talk about "check" (threat to capture the king in the next move) and "checkmate" (unstoppable "check"), but taking these concepts out of the game rules make them much simpler to state.

mangue: Very nice! Even though in classical chess sacrifice with mate in 4 isn't that unusual, it's because players are familiar with checkmating schemes, but to find such in this new game must be something very pleasant.

well, i have a definite answer now, got from experience. one's opponent can definitely move one's king into check and then merrily gobble it up.

WhisperzQ: okay. thank you very much.

plaintiger: I understand that your opponent can move whichever piece they chose so long as it is a valid chess move for that piece (checks not taken into account) ... so if your King could move there they could move your King and then they would click on the square on which your King resides and you would need to select one of their pieces to move to take your King, in this case the queen would suffice.

...which i'll ask here rather than bug nabla with every niggling thing that comes through my head:

the rules for ambiguous say there's no check or checkmate, but if the goal is to capture the opponent's king, and my opponent's queen is staring down and open file at my king, i consider myself to be in check. so: is ambiguous like regular chess in that i (and so my opponent) is/am obligated to protect my king when possible?

in other words, if i have this above-described situation, and i click a square between my opponent's Queen and my king, and any of several pieces could move there including my king, whose moving there would leave him in "check", can my opponent move my king to that square and then take him on his next move, thus winning the game? or is he obligated to move some other piece to that square, thus protecting my king?

thank you.

my most beautifoul sacrifice :
http://brainking.com/en/ArchivedGame?g=1665304&i=18

Harassed: When I have played the game, most mates have come by errors. When I actually had to mate in one game, it was rather difficult even though I had a nice piece advantage.

yes, maybe

mangue: May be good way to resolve this would be to ask excellent chess variants players like: Matarilevich, Ughaibu, Oliottavio, Reza, Tenuki, Pythagoras, Nabla, Pioneer54, Anencephal and others, what do they feel when they play this game together.

nabla: .
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You are concerned about Pawn promotions right?
Hmmmm.... I know as the level increases you will see that more and more games will be decided at Pawn promotions so this could be a problem.

Remember: Chess would not be what it is if there wasn't the Pawn promotions!
Most of the times if you outplay your opponent you will not win immediately by mate but just obtain a material advantage like a Pawn more or Knight for 2 Pawns etc....
So most times you will have to find a way to promote that Pawn or to use your Knight to help your Pawns to promote while your King stops the opposite Pawns or the opposite or just capture tha opponent's Pawns, but the extra Knight doesn't win alone if a Pawn doesn't promote! And most of the times it should promote to a Queen to win.....

So i guess you will need to change the rule one time or another but we will see....

Pythagoras: I like the games with balanced results. Atomic and 3-checks for example have a clear advantage for white (ok, I still like them ) . Maharadjah and Horde are simply unfair. The player starting at ambigous has certainly an advantage. Like in CHESS, and here on brainking.com, blacks wins more often than white at regular chess, probably because some feeble beginners play only with white

mangue: Thank you ! It is true that these are very good stats, but Pythagoras is also right that it is too soon to tell what will happen later. I am still concerned about the possibility that there may be too many drawn endgames in the future.
For the moment, the game seems to work even better than I had thought

grenv:.
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OK then.... But why do you keep refering to a possible white advantage specifically? I've seen this from others too. You assume that if this game is not balanced and there is one side that has the advantage this side is white.
Why you don't even consider black for having the advantage....?