Queens are kings and kings are queens (obviously), but when one player’s pawn reaches the other player’s back row it has to be replaced with a backgammon piece
Knights can only move backwards, rooks can only move in circles
If one bishop moves, all bishops move; this is called synchronized prelacy
Middle row on both sides populated by invisible Borgia pieces, which can’t move but can poison the piece directly in front of them; both players still have to do the work of individually cancelling one another’s Borgias out
Check is illegal
Every move is checkmate
Pawns now supported by a booster row of light infantry
Additional pieces include dragoons, Hessians, imperial guards (which are not allowed to attack), Angevins (which can only move in French), Aethelred the Unready (cursed piece, cannot move), Waltzin’ Empress Matilda, the White Company of John Hawkwood (must move as a collective), brigands, highwaymen, Dauphins, longbowmen (only allowed to resolve the Hundred Years’ War, cannot attack queens-as-kings), trebuchets, Scotsmen, caliphs, El Cid (as long as El Cid remains in play both players must remain standing), M.C. Escher stairs, the Order of Indulgences, Witchfinder General, Witchloser General, optional Vikings, a deer park sanctuary, the King’s hangsman, the King’s deer, the White Hind, the Grail and the Lance, popes and antipopes, and Prester John.
I need to learn to play an instrument so that I can start a band called "Optional Vikings."
(And I so badly needed to comment this that I finally subscribed. Sorry it's taken me so long.)
> Queens are kings and kings are queens
I totally started singing Run-DMC's "Raising Hell" after reading that.