An excellent to this game!

Maybe the author has not read the comment below, otherwise he would have been frightened by the task he has underdone. On the other hand: Can a Spartan be frightened?

http://www.chessvariants.org/piececlopedia.dir/chess-different-pawns.html

--JKn

I'd say Steven hit a home run, even if he didn't hit this one clear out of the park. Let me quote the last 2 lines of the Betza article Jorg refers to, Different Pawns.

'If you can find alternate Pawns, I will be in awe, taking my hat off to you.

And, to keep you from feeling complacent, I'll ask you to try chess with different Kings. I now fade away, leaving nothing behind but an evil grin.'

Spartan chess, with its pair of kings, is halfway between FIDE and Gary Gifford's Three Elephant Chess. http://www.chessvariants.org/index/msdisplay.php?itemid=MSthreeelephantc You may argue the kings aren't quite different enough to fulfill Ralph's requirements. Still, Steven nailed the different pawns and also managed to put 3 kings on the board in the same 2-player game. That's a nice, high benchmark for the rest of us to go after.

Because of the asymmetry of this variant it required some special attention to make sure the diagram would only allow each side to promote to its own pieces. What I did was define the promotion choice with an asterisk before each piece, meaning it can only come from the holdings. Then I stuffed the holdings initially with eight of each eligible piece type (enough to promote all Pawns to it).

Except for the Spartan King, which would only be a valid promotion choice if one of the Kings was captured. So I defined the holdings type such that it would accumulate captured pieces of the original owner. By starting without Kings in hand the Spartans then can only promote to King when one of their Kings is captured.

Castling

Only the Persians can castle, and this forced the Persian and Spartan Kings to be defined as different piece types. (If castling is specified with the aid of an O atom, the diagram assumes it is with a Rook or a corner piece of any type. And we do'nt want the Spartan Kings to castle with their Lieutenants!) This has the dubious effect of the Spartan Kings not being considered royal (as the diagram only considers one piece royal, by default the last one defined). So moves of Spartan Kings into check are not 'grayed out', like they are for the Persian King. But of course this is justifiable, as the Spartan King can actually expose itself to capture (if there still is a second one). So such moves can be legal. The diagram does not understand extinction royalty.

I don't usually like games with different armies, but this is an exception. You've put a lot of thought into making a game whose different armies are not unevenly matched. For sure, the Spartan side lacks a Queen and its army appears to be slightly less powerful, but that is compensated for by the presence of two kings, both of which must be checkmated/captured.