Speaking of interesting chess variants

The thing about PGN compatibility is that you have to be able to load it up into anything that would read PGNs and not have it complain about irregularities. Two moves per side in Marseillais chess is definitely not PGN compatible. 'No' chess, on the other hand, is.

'No' I think from explanation, as i have never played it, is 100% pgn compatible. But it is not fun playing this variant. Just a guess.

It is probably not PGN compatible, but I like Progressive Chess (www.chessvariants.org/multimove.dir/progressive.html). Are Kriegspiel (www.chessvariants.org/incinf.dir/kriegspiel.html) and Avalanche chess (www.chessvariants.org/mvopponent.dir/avalanche.html) PGN compatible?

I've also invented a chess variant myself. Is Hop the King Chess PGN compatible?

Hop the King Chess follows the rules of regular Chess except for one rule: you can hop over your King with your riders (bishops, rooks, queens) as if the King is not there. You can play such moves as often as you want and your opponent can do the same with his/her King. You cannot hop over the King of your opponent because that would mean that it is your turn while the King of your opponent is in check (it is against the rules of regular Chess to make a move that puts or leaves a player's own King in check).

I've come up with one of my own as well: Queenless chess.

There are no queens, the board is 7x7, and the knight and bishop on the "long castling" side are swapped so there's both a dark and light squared bishop. All the rules as well as en-passant work the same. The aim is to remove the over-poweredness of the queen and base the game around the weaker pieces.

I see to problem with my suggestion with crazyhouse. We need to have some sort of efficient way to "play" the moves.

It is like allowing other pieces to jump over King, but only king and not each other. It is PGN compatible i think as no additional symbols needed in notation. 'Hop the King' can be recorded using pgn.

What would the move "numbers" be then? :)

I don't believe Hop the King would be PGN compatible. Those would be entirely illegal moves in regular chess which PGN-readers would complain about, saying that the piece simply can't be moved there. PGN compatibility is about retaining those moves and redefining win conditions, like KoTH where an additional win condition is granted on getting your king to the centre. If a KoTH PGN were read in a regular chess viewer, it'd look just like a regular game, as if the opponent resigned the moment your king got to the centre.

It seems to me that there's call for an extended PGN format, something like .pgnx or .xpgn (I favour the first, but they should probably be interchangable). It may never be accepted by FIDE, but that's hardly the point. I'm thinking along the lines of XHTML incorporating more of XML and SGML into HTML. So .pgnx would include the entire PGN specification and then add those things necessary to display variants (e.g. the @ for use in Crazyhouse and so on).

Besides, I believe PGN came from a post on USENET (albeit adapting existing algebraic notation), no reason why we can't solve this other thing here.