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This page is written by the game's inventor, Charles Daniel.

Stealth Ninja Chess

  1. The game is played on a 104 square board with 2 extra squares that protrude from the center of each side’s back rank. These squares are "in-play" throughout the game just like any other square on the board, but they are also special squares since they allow the entry of two new pieces during play.
  2. Each side starts with two Ninja Warriors , two Ninja Guards, two Rooks, two Bishops, two Knights, King, Queen and 10 Pawns that are setup using one of two possible starting configurations.
  3. The two new pieces, the Ninja Guards and the Ninja Warriors are short-range 2 space leapers and single space steppers. The Ninja Guards move along diagonals only, and the ninja warriors, orthogonal. More info.
  4. Play progresses as in chess, but each side has the option during any move to drop the following:
    1 Stealth Gryphon - A powerful sliding piece that controls two files and two ranks.
    1 Stealth Anti-Gryphon - Analogous to above but controlling multiple diagonals.
    4 Ninja Pawns - A stronger pawn capable of capturing sideways in enemy territory.
    > > more info.
    The stealth gryphon or anti-gryphon can enter only via one of the two rear squares. The space must be empty and the drop is considered one move.
    The ninja pawns can enter via any vacant space on the 2nd rank.
    The ninja pawn can be pushed forward towards the center (1-multiple spaces) on the same move.
  5. The standard pawns advance 1-3 empty spaces from their start position and 1-2 spaces from the third rank (rank 8 for black) towards the center.
    En-passant is extended for these conditions. If a pawn bypasses an enemy pawn by moving 2 or 3 spaces forward it can be captured en passant.
  6. The castling rules have been modified. The King can transpose places with the rook by moving multiple spaces towards it. There are a total of 7 castling positions.

Setup


Stealth Ninja Chess Main Start position

Coordinates for white. (black mirrors white)

Ninja Guards on a1, j1
Rooks on b1,i1
Knights on c1,h1
Bishops on d1, g1
Queen on e1
King on f1
Ninja Warriors on e0,f0.
Stealth Ninja Chess Start position Alternate start position
Coordinates for white. (black mirrors white)

Rooks on a1, j1
Knights on b1,i1
Bishops on c1,h1
Ninja Guards on d1, g1
Queen on e1
King on f1
Ninja Warriors on e0,f0.

Pieces

The Ninja Guard

Movement: The Ninja Guard is a color bound piece that can move one or two steps diagonally. It can leap over a diagonally adjacent piece to land exactly 2 squares away (a two-space diagonal leap).
Capturing Mechanisms: It can capture by replacement on any square it lands.
It also can capture any diagonally adjacent enemy piece by jumping over it. It is mandatory to capture when jumping over an enemy piece.
It can capture two pieces (the first immediately adjacent to it, and the next right after) in its diagonal path by jumping over the first one and capturing the second piece on the square it lands.

The Ninja Warrior

Movement: The Ninja Warrior can move one or two steps orthoganally. It can leap over a piece to land exactly 2 squares away (a two-space orthogonal leap).
Capturing Mechanisms: It can capture an enemy piece by displacement by moving into its square.
It can also capture an adjacent enemy piece by jumping over it. If jumping over an enemy piece this capture is mandatory.
It can capture two pieces (the first immediately adjacent, and the next right after) in its orthogonal path by jumping over the first one and capturing the second piece on the square it lands.

Reinforcements

The Ninja Pawn

The ninja pawn possesses slightly different modes of movement and capture depending on which half of the board it is on.
Movement:
The ninja pawn can always move 1 square up or 1 square sideways to an empty square from any part of the board.
When the pawn is situated in the lower half of the board (for White, rank 0-5 and for black 11-6), it can move forward multiple vacant squares (1-3 squares) to reach the middle of the board (rank 5 for White or rank 6 for Black). This move can be done at any time regardless of how many times the pawn has moved.
Once it passes the middle, the ninja pawn can only move 1 square forward at a time, or move 1 square horizontally.
Capture:
Like the standard pawn it can capture one square diagonally up, regardless of which half of the board it is on.
When the ninja pawn is on the top half of board (White rank 6 +, Black rank 5-) , it can also capture one square horizontally.
There is no en passant. It cannot capture another pawn or ninja pawn en passant nor can any other pawn capture it this way.
Promotion: The ninja pawn promotes on the last row (rank 10 for white, rank 1 for black), to any piece. Promotion to a piece is mandatory so it would cease to be a pawn in the last row.
Dropping:
The ninja pawn is not present at the start at the game and is dropped by the player into the ninja pawn drop zone, which are the 2nd rank squares . For example, the drop zone for white is a2-j2 and for black a9-j9.
The square must be vacant to drop the pawn. You can drop a pawn to check or to checkmate the opposing king. A maximum of 4 ninja pawns can be dropped by each side during a game.
After dropping a pawn, the player can optionally move the ninja pawn forward 1 or multiple squares towards the center on the same move. A capture or a side move is not permitted during the drop, so the player can just drop a pawn, or drop a pawn and move it 1-3 vacant squares towards the center.

In diagram, the black ninja pawn can go from e9-e6 or any other square in between or d9 or f9. The white pawn at f7 cannot capture it en passant.

Lets say the white ninja pawn went from e3-f3 , it still has the option of shooting forward to the middle (f5) regardless of how many moves it made before.


The white ninja pawn at h9 can capture the bishop at i9 in addition to being able to go to g9 or to promote by going to h10.

The two pieces below can also be dropped into the game but only unto the 2 outer edge squares as described in the rules.

The Stealth Gryphon

The Stealth Gryphon is a potentially powerful piece that can control multiple files and ranks if used effectively, and its awkward move can catch an unsuspecting opponent by surprise.
Movement/Capture by replacement: It must move along any unobstructed path (it cannot leap) of 1 square diagonally followed by 2 or more squares horizontally or vertically outwards. Thus, it can reach its destination square only one way but it can exert a powerful influence when not blocked.
The Achilles heel of the Gryphon (and the Anti-Gryphon) is its susceptibility to having its path blocked, and its vulnerability to close range attack.
Partial board shows white king on e0 and black Stealth Gryphon on h1. Red is "offboard".

Here the griffon is hampered by the edge of the board but still exerts great influence.
It controls the squares in yellow but it is not checking king because it needs to go one diagonal first and then 2 or more orthogonal outwards and there is no such path towards the king.

The Stealth Anti-Gryphon

The Stealth Anti-Gryphon is the exact inverse of the Stealth Gryphon, and so controls multiple diagonals.
Movement/Capture by replacement: It must move along any unobstructed path (it cannot leap) of 1 square horizontally or vertically followed by 2 or more squares diagonally outwards.
Partial board shows black Stealth Anti-Gryphon on e4. Note that it will control more squares on the actual board.

Anti-Gryphon shown controls the squares in yellow. Notice its long-range prowess but short-range vulnerability. Esp note how easily a piece can block its path.

Rules

The rules in Stealth Ninja Chess are the same as in chess except for using the new pieces and for the following modifications :

  1. Reinforcements - Dropping pieces

    Players can drop:
    One Stealth Gyrphon and one Stealth Anti-Gyrphon in the manner described below:
    • A piece may be dropped on any empty rear square (e0,f0 for white, e11,f11 for black) at any time.
    • Dropping a piece constitutes a move.
    • A piece can deliver check or checkmate when dropped.
    • A piece can block a check when dropped.
  2. Reinforcements - Dropping 4 Ninja Pawns. There is a special promotion zone and associated drop rule for Ninja Pawns.
    The ninja pawns can be dropped into any empty square on the 2nd rank. And, the Ninja Pawn can be optionally pushed forward (1- multiple empty spaces) on the same move.
  3. Castling: The usual castling criteria apply: No piece must be in between the spaces travelled by the king and castling rook, cannot castle out of check, King cannot pass over or land on squares attacked by enemy, but rook can.
    Castling is flexible with the king able to travel 1, 2, 3, or 4 squares towards the rook and the rook right next to the king on the other side. There are 7 possible castling positions, the most extreme wing castling being the king going to the b or i file. The choice of castling positions will depend on whether it is immediately necessary for the king to be nearer the wing or for the rook to be centralized.
  4. Pawn moves: The pawn can move from its original position either 1, 2 or 3 vacant squares forward.
    A pawn situated on the lower half of the board can at any time move forward 1-3 vacant squares to reach the center of the board (rank 5 for white, rank 6 for black). Once the pawn reaches the center row, it can move forward only one square at a time.
    Some examples: The white pawn at f2 can start f2-f5 or it can move f2-f4 then f4-f5, or f2-f3 followed by f3-f5, or move f2-g3 to capture enemy piece at g3 followed by g3-g5 next time it moves.
  5. En Passant: If a Pawn moves two or three squares initially and passes an opposing Pawn on the fourth or fifth rank, the Pawn may be captured en passant. E.g. White pawn on a2 black pawn on b4. If the white pawn moves from a2 to a4 or a5, the black pawn on b4 can capture it as if it had moved to a3. Similarly, if the black pawn is on b5 instead and the white pawn moves to a5 from a2 then the black pawn can capture the white pawn as if it moved to a4. Note in this case the white pawn can still avoid the black pawn by moving to a3 instead.
    If a pawn slides forward 2 squares on its second move, it can also be captured en passant by an opposing pawn on the fifth rank. E.g. white pawn on a3 and black pawn on b5. White plays a3-a5, black pawn on b5 can capture the pawn en passant by moving to a4.
    Capturing en passant is optional unless it is the only legal move available. The capture must be made on the next move.
  6. Pawn promotion: Pawns can promote to: any piece (except the ninja pawn) on the 10th rank only.

Notes

Sample Games

Below are some sample games that can be viewed with the Game Courier system.

Blunder by white /back rank

Battle Rages on

Experimental Rules

It is advisable for players to start of with the default rule-set: Board 1 with ability to drop 4 ninja pawns, Gryphon and Anti-Gryphon. This setup is the very essence of the game.
Once familiar with the game, the alternative pieces: Flying Bomber and Super Cannon can be also be tried to produce very interesting gameplay.
Then the other rules: piece promotion, capture the scepter can be tried, as well as different configurations with board 2.

Alternative Reinforcements

Instead of the Stealth Gryphon and Anti-Gryphon, the Super Cannon and Flying Bomber described below can be used.

The Super Cannon

Movement: When not capturing the super cannon moves like a rook. It can also jump over an adjacent friendly piece to land 2 squares away. Note that it cannot jump over an enemy piece in this manner.
Capturing: The Super Cannon like the Cannon in Xiangqi needs an intervening piece called the screen to make a capture. The screen can be either a friendly or enemy piece and must lie between the cannon and the enemy piece for a capture to take place.
With a friendly screen, the Super Cannon captures the enemy piece by leaping over the screen and landing on the target's square.
If the screen is an enemy piece then the firing mechanism of the Super Cannon is altered to destroy both its target and the screen at the same time! Thus, it takes out both enemy pieces after it lands on the target enemy piece's square.

The Flying Bomber

Movement: When not capturing it moves exactly like a rook (1 or more squares orthogonally over a clear path).
It can also jump two squares orthogonally by leaping over an adjacent piece.
Capturing: The flying bomber eliminates an enemy piece by flying towards it in a unobstructed orthogonal path, and landing on THE empty square immediately after. It cannot capture if this square is occupied nor can it capture a second piece.
The exception to above: the flying bomber can capture by replacement any enemy piece that is 2 squares away. Thus, it can jump over a friendly piece to make a capture 2 spaces away. If, instead, there is one empty square between the Flying Bomber and the enemy piece, the Bomber can either capture by landing two squares away on the target's square or use the standard method of capturing by landing on empty square immediately after target.
If there is one enemy piece adjacent to it and another immediately after on same line, the flying bomber combines both capture mechanisms to makes a double capture as it lands 2 squares away. Note that when it makes this jump under above conditions capturing both pieces is mandatory.
See more details and diagrams describing this piece here.

Ninja Piece Promotion - The Insane Ninja

The Ninja Guards or Ninja Warriors can promote to more powerful versions - Insane Ninjas, if they can safely land in the opposite side's rear squares. Thus, for promotion, white's ninja pieces must occupy e11 or f11 or black's must occupy e0, f0. The Insane Ninjas combine the movement/capturing modes of the Ninja Guard and Ninja Warrior.

Capture the Scepter

Each side stores a scepter in the rear center squares (e0, f0, e11,f11). If the opposing king can occupy any of these squares (e11,f11 for white or e0,f0 for black), the game is drawn.
This rule is best used in conjunction with the Ninja Piece Promotion rule. It allows an extra resource for the weaker side. An example of possible use: one side is down to a bare king while the other is up a ninja guard. The stronger side can easily promote the Ninja Guard to Insane Ninja and win, but if the weaker side's king can reach the opposite side's rear squares safely, the game is drawn.
This rule is almost identical to the rule with same name for Birds and Ninjas. The difference is in the outcome of the game. Here the game is drawn while in Birds and Ninjas it is a win for the side that captures the scepter.

Alternative Setup

Instead of using the orignal board, use an alternative setup with a more powerful pair of Ninja Guards: the Leaping Ninja Guards.
Ninja Warriors on a1, j1
Rooks on b1, i1
Knights on c1,h1
Bishops on d1,g1
Leaping Ninja Guards on e0,f0
Queen on e1
King on f1 The Leaping Ninja Guards move exactly like the Ninja Guards but also have an extended 3, 1 leap: 3 squares orthogonal 1 square perpendicular. When using this mode of movement, they capture by replacement. (The jump over capture is reserved for the 2 square digonal leap).

This 'user submitted' page is a collaboration between the posting user and the Chess Variant Pages. Registered contributors to the Chess Variant Pages have the ability to post their own works, subject to review and editing by the Chess Variant Pages Editorial Staff.

By Charles Daniel.
Web page created: 2008-03-28. Web page last updated: 2008-08-08