Four-Player Infinite Chess - The Battle of Morgarten!

There's probably one more thing that needs clearing up.

Are you allowing a move like Kd3?

It's probably less complicated if the king simply cannot move once checkmated.

Oh, you covered it here. Ignore me, as you were...

21.Qx(-1,14)+

When a king is put into checkmate, then the opponent can capture the king on the very next move. But it's not mandatory.

Also, the way I see it is this: An army can keep playing without his king, so the player is still involved. A player can keep playing as long as he has at least one piece on the board.

If a player has lost all his pieces, I suppose it's at that point the the player has nothing to do (except talk with his teammate).

"But it's not mandatory."

This opens up the possibility of the king being "released" from checkmate before it is captured. And if the king is dead, why waste a tempo capturing it? Perhaps the most simple solution is a checkmated king is immediately removed from the board. Either that, or a king that is "released" from checkmate becomes "alive" again, thus giving the incentive to immediately capture the king unless there truly are better options available.

 You either have to take the checkmated king off the board immediately, or forbid it from making illegal moves, ie capturing a protected piece. If it's the latter, well if the checkmate is released before capture, then the king has legal moves again. So the incentive is there to waste a tempo capturing the king, but it's not mandatory.

That seems simple enough one way or the other. The latter is probably better imo, but the former is brutally simple.

But if the king is in checkmate, he can move any other piece?

Black plays 50...Qd4#

(so White to move).

Is this allowed?

51.Nf5+

That's a fine aspect to think of...

One solution is for a player to always skip their turn if they have no legal moves or has lost their king. Since they have no legal moves when they are checkmated their turn will be skipped. This would allow for a 1 vs 2 scenario after a king gets captured and prevents the game from ending in stalemate if a player has no pieces left.

Not sure if it is just me, but I am not a big fan of an army to keep fighting after they lost their king or to have special rules of what moves are legal when a king gets checkmated.

I agree with Martin0 !

If the king is checkmate, he can't move out of the check and therefore he can't make another move. It can't be that any other move is made while the king is in check(mate). This contradicts all known chess rules.

Since they have no legal moves when they are checkmated their turn will be skipped.

But if the king is no longer in check, or when the King is CAPTURED, then and only then the former checkmated player take again control of his pieces and it is now immediately allowed to continue playing the captured king's pieces for the team.

I helped make the rules for this particular version, but others have helped too. But it's impossible to know who first studied "infinite chess". If you google it, it gets studied a lot by mathematicians. Example here:

But as far as I know, this is the only place where it is played for real. And we made it better (or worse?) by making it a 4-player game.

I agree with captaintugwash (his latter interpretation). 

I just assumed that with two kings, there is redundant royalty. If one gets captured, everything is pretty much the same because the other king is still on the board. Everyone can keep playing until the second (and last) king is checkmated.

The first king being checkmated is really no different than a piece which is attacked, and there is no way to avoid capture (same as normal chess for any piece).

I took this to be the most "faithful" interpretation of normal chess.

Since we have different points of view, I guess no decision yet.

Btw, where is Luke_Hands?

Yes that would be allowed (with what I believed). This could follow:

51.Nf5+...Ke-f6 (White forks K and Q - Black must parry the check).
52.NxQ...PxN
53.KxP

(White's fork wins the queen involved in checkmate, so White's king is rescued. Play continues).

You agree with Tug's first idea, I agree with Tug's second idea. McGoohan and Martin0 have other interpretations altogether.

Removing a checkmated king from the board directly also sound fine.