The rules of DualLife Chess
DualLife Chess is ordinary chess with one change, and the change reaches everything. Every piece carries two points of life instead of one, so nothing is removed from the board by a single blow. What follows is the complete ruleset.
Two lives, every piece
Every piece begins with two points of life — pawns and kings included, with no piece harder or easier to hurt than another. A piece at two points is whole. A piece at one point is wounded, and it stays on the board, and it moves and captures exactly as it always did. Damage is permanent: nothing heals a wounded piece for the rest of the game.
The first hit wounds, and your piece does not move
Move onto a whole enemy piece and you take one point of life from it. It stays on its square, now wounded. Your own piece stays where it started, because the square it was moving to is still occupied.
This is the rule that separates DualLife Chess from everything it resembles. A capture in ordinary chess is a move and a removal at once; here the two come apart. You have spent your turn, an enemy piece is weakened, and the position is otherwise exactly as it was.
The second hit takes the square
Move onto a wounded enemy piece and it is destroyed. Your piece advances into the square and the move resolves exactly like a capture in ordinary chess. Removing any piece therefore costs two moves — and they need not be consecutive, nor made by the same piece. Anything that can reach the square can deliver the second blow.
No check, and no checkmate
The king has two points of life like everything else, so a single attack cannot end the game and there is nothing for check to warn you about. There is no check, no checkmate, and no rule forbidding a king from moving into an attacked square. You may walk your king into fire and survive it — once. The game ends when a king is actually taken, which means an opponent has struck it twice.
Castling needs an unhurt king and rook
Castling requires what it always did: neither the king nor the rook has moved, and the squares between them are empty. It requires one thing more here — both must be at full health. A single hit on either the king or that rook removes the castling right permanently, and nothing can restore it, because nothing heals.
One rule of ordinary chess does survive here, and it is the exception worth remembering: the king may not castle through, or onto, an attacked square. On any other move it may step into an attacked square by choice and simply take the hit — but not while castling.
A wounded pawn promotes into a wounded queen
A pawn reaching the far rank promotes as usual to a queen, rook, bishop or knight, and it may promote on the same move that destroys a piece. What it cannot do is arrive whole if it did not set out whole. Promotion changes what a piece is, not how much life it has left: push a wounded pawn to the last rank and you get a queen that dies to one hit.
En passant, in two stages like everything else
En passant is available on the same terms as in ordinary chess and resolves under the same two-stage rule. If the captured pawn was whole it is merely wounded, it stays on its square, and your pawn stays on its own. If it was already wounded it is destroyed and your pawn completes the move.
How games are drawn
A player with no legal move on their turn draws the game — stalemate, as in ordinary chess, though reached differently, since there is no check to be escaped. Players may also agree a draw at any point. There is no fifty-move rule and no draw by threefold repetition.