A couple people offered to playtest this, so here it is. World Tree's Diamond Chess is played on (usually) an 8x8 board, like a chessboard, but turned so that one point faces each player. There are four colors of squares:
- Black City: One corner is black; this is the black player's city. The white player wins by getting a piece into this square.
- White City: The opposite corner is white; the black player wins by getting a piece into it.
- River: The eight squares along the diagonal are the River, and colored blue. Special rules apply to them.
- Flats: The remaining squares are flats, unpainted, and have no particular behavior.
Each side has eleven pieces: one for each prime species, except three cani. At the start of the game, Black and White, in that order, alternate placing four pieces on the board, one in the town, the others in the three squares adjacent to the town. The remaining pieces are held in reserve. After that, Black takes the first turn.
A turn consists of:
- Optionally, mustering: taking a piece from reserve and putting it in your city, if your city is empty.
- Moving and/or using the powers of one species: that is, one piece, or 1-3 of the cani.
Play proceeds until one side has gotten a piece into the other's city. If, at any point, no pieces have been taken in seven turns, either player may ask for twelve turns to stalemate: if, after each player taking twelve more turns, no pieces have been taken, the game is a draw.
If, at the start of a turn, you have a piece in reserve and your city is empty, you may take a piece out of reserve and put it in your city. You may muster a piece and use it on the same turn if you wish.
Captures are either "by spear" (by moving the capturing piece onto the victim's square), or "by arrow" (in which the capturing piece takes a piece on an diagonally adjacent square before it moves). Pieces capture by spear only unless otherwise stated.
The River: All pieces but the orren treat the river as a partial obstacle. If their move passes over a river square, they must stop on that square. (So, some diagonal moves are not obstructed by the river, others are. All orthogonal moves are obstructed by the river.) A non-orren piece that starts its move in the river must move out of the river on that move, or is taken. Pieces that can move diagonally or knightwise can cross the river in a single move
The cani: A solitary cani can move one square orthogonally. Two orthogonally-adjacent cani can each move 1-2 squares orthogonally. If all three cani are orthogonally adjacent in a line, each of them can move 1-3 squares orthogonally. If they are adjacent in a right triangle, each can move 1-4. This is one of the few ways to move more than one piece in a single turn. They do not need to wind up adjacent after moving. Cani capture by spear.
The gormoror: The gormoror moves 1-2 squares orthogonally. It can capture by arrow and by spear in the same move: by arrow before it moves, by spear at the end of its move.
The herethroy: The herethroy moves any number of squares orthogonally. It captures by spear. It cannot be captured by arrow.
The khtsoyis: The khtsoyis moves 1 square orthogonally, and captures by spear. If it captures on its first move, it may act a second time, either moving or capturing. If it captures twice, it may capture a third time, though it may not move a third time if it is not a capture.
The orren: The orren may always move one square or "all the way" orthogonally (but nothing in between the two). "All the way" means going orthogonally until it can go no further: it may run into an edge of the board, or stop because the next square would contain a friendly piece, or stop because it has captured an enemy piece by spear. The orren may also stop in the river, if its move passes through the river. If the orren starts its turn in the river, it may move to any other river square as its move, including capturing a piece there by spear.
The rassimel: The rassimel moves one or two squares, orthogonally or diagonally. It captures by arrow.
The sleeth: The sleeth moves can move one or two squares orthogonally, or any number of squares diagonally, making it the most mobile piece. It captures by spear. (A sleeth placed on the diagonal line connecting the cities threatens a quick win.)
The zi ri: The zi ri moves one square orthogonally. It can also teleport itself or one other piece (of either side), moving the subject in a knight's move to an unoccupied square. It can teleport one piece per turn, which may be done before, after, or instead of its movement. The piece being teleported must be visible to the zi ri; viz. there must be a diagonal or orthogonal line to it that has no other pieces between the two. The zi ri can see across the river. Teleporting a piece over the river is allowed. Teleporting a piece into the river is allowed also. A piece teleported into the river is in the river as usual; orren can swim, and non-orren have to leave on their next move or be taken. The zi ri has no attack per se. (A well-positioned zi ri can teleport a piece into the enemy city, winning the game.)
(If you get to playtest this, tell me the results. Suggestions welcome. As on the World Tree, there is no particular effort to make the pieces balanced. But they should all be good for something.)