I didn't know this existed before... well, just now, pretty much.

http://play.chessvariants.org/pbm/play.php?game=Seirawan+Chess&settings=Seirawan+Chess

It works pretty darn well, except the website takes some getting used to.. and you do need to register.

The move syntax is like this:  "b1-c3;A-b1" = Knight to c3 (obvious) & drop a Hawk (piece "A" on the chart below the board) on b1.  If you aren't dropping one of the special pieces, you can just move via mouse-clicks.

I'm DeepGreene on that server as well, if anyone wants to try it out.

DeepGreene, I hope you don't mind, but I challenged you to a game of s-chess on chessvariants.org. If you would rather play via the forums, tell me now and I would happily oblige. My ID is iamcleverbot.

No problem!  Accepted.  :)

Now please do me a favor and tell me how to log on to my account to play the game.

Haha!  Hmm... too bad this isn't a timed game.  :)

Been a while since I've used it, but I think you should have gotten an email when I accepted and moved (?).  I got one when you challenged me and it took me straight to the game:  I just needed to enter my password and hit the "continue" button (not sure why) and then I could move.  (There's also a My Games area where you can see all games where you have the move.)

You can make a normal move by clicking squares per usual.  Dropping a hawk or elephant onto the board actually requires some special syntax I described above.

I have now implemented a much better online S-chess script here:

http://www.chessvariants.org/index/msdisplay.php?itemid=MPseirawanchess_

It checks the validity of moves, etc.

Ooh, that looks great!  Thanks for the update.

Try it out by pressing the 'move' button. The script asks whether an external piece shall be introduced.