Trojan chess

In Trojan Chess, all the rules of traditional chess apply, including the initial positioning of the pieces. The main difference between Trojan Chess
and traditional chess is the change in the rules and behavior of the Knight piece. Namely, the Knight piece additionally contains a Pawn,
which can detach from the Knight during the player's move by placing it on one of the four squares next to the Knight along a horizontal
or vertical line ( from above, below, to the left or to the right of the Knight ). After separating the Pawn from the Knight, the Knight
changes into a new piece - the Horse. The Horse moves like a traditional Knight but cannot capture or be captured by enemy pieces.
A Horse can become a Knight or Royal Knight again by capturing its own Pawn or King. The second way to turn a Horse into a Knight
or Royal Knight is to move a Pawn or King from a horizontal or vertical direction to the square occupied by its Horse.
In this case, the Pawn can move sideways or backwards to get on the Horse.

Rules

Game rules:

1. Knight ( Horse + Pawn = Knight )
- The Knight moves and captures just like in traditional chess.
- The Knight piece contains a Pawn which, when separated, turns the Knight into a Horse.
- The Horse moves like a traditional Knight but cannot capture or be captured by enemy pieces.

2. Separating the Pawn from the Knight ( Knight – Pawn = Horse )
In his turn, a player may:
- make a move with the Knight as in traditional chess.
or
- place the Pawn on one of the four squares next to the Knight ( from above, below, to the left or to the right of the Knight ).
After placing a Pawn, the Knight turns into a Horse.
or
- he can first make a move with the Knight without capturing the opponent's piece and then place the Pawn on one
of the four squares next to the Knight ( from above, below, to the left or to the right of the Knight ). After placing
a Pawn, the Knight turns into a Horse. A player cannot detach the Pawn from the Knight if he has made a move in which
he has captured an opponent's piece.

* When a Pawn leave the Knight, it cannot capture enemy pieces.

3. Promoting the Horse into a Knight ( Horse + Pawn = Knight )
A player can promote a Horse to a Knight in the following ways:
- While moving, the Pawn can enter the square occupied by a friendly Horse only from horizontal
or vertical directions ( from above, below, to the left or to the right of the Horse ).
After such a move, the Horse turns ( promotes ) into a Knight.
- if the Horse moves to a square occupied by a friendly Pawn - the Horse changes ( promotes ) into Knight.
During this move, the Pawn cannot separate from the Knight.

* By moving a Pawn two steps from its starting position, a player cannot place it on the square
occupied by a friendly Horse and promote it to a Knight.

4. Royal Knight ( Horse + King = Royal Knight )
Royal Knight moves and captures like a traditional Knight, but can also be put in check or checkmated.
When a Royal Knight is in check, he cannot move like a traditional Knight.
During check, the Royal Knight can only make a move just like a traditional King or the King can leave the Royal Knight.

5. Promoting the Horse into a Royal Knight ( Horse + King = Royal Knight )
A player can promote a Horse to a Royal Knight in the following ways:
- While moving, the King can enter the square occupied by a friendly Horse only from horizontal
or vertical directions ( from above, below, to the left or to the right of the Horse ).
After such a move, the Horse turns ( promotes ) into a Royal Knight.
- if the Horse moves to a square occupied by a friendly King - the Horse changes ( promotes ) into a Royal Knight.
The King cannot separate from the Royal Knight during this move.

6. Separation of the King from the Royal Knight ( Royal Knight – King = Horse )
In his turn, a player may:
- make a move with the Royal Knight just like with a traditional Knight.
or
- place the King on one of the four squares next to the Royal Knight ( from above, below, to the left
or to the right of the Royal Knight ). After placing the King, the Royal Knight then turns into a Horse.
or
- he can first make a move with the Royal Knight without capturing the opponent's piece and then place the King on one
of the four squares next to the Royal Knight ( from above, below, to the left or to the right of the Royal Knight ).
After placing a King, the Royal Knight turns into a Horse. A player cannot detach the King from the Royal Knight
if he has made a move in which he has captured an opponent's piece.

* When a King leave the Royal Knight or Royal Unicorn, it cannot capture enemy pieces.

7. Transfer from a Horse to another Horse
If during the game, the Knight, Royal Knight, Archbishop or Chancellor lines up in a horizontal or vertical line
next to the Horse, the Pawn, King or Queen may move to that Horse.

8. Pawn promotion
When a Pawn takes the seventh or eighth rank after leaving the Knight, that Pawn is immediately promoted to Prince.
The Prince moves like the King but only captures diagonally. The Prince can also use the Horse to move.
If the Prince uses a Horse to move, he is demoted to a Pawn.
In other cases, Pawn promotion is as in traditional chess.

9. Extra Horse - OPTIONAL RULE
Each player has an additional Horse that does not take part in the game at the beginning. If a player
loses both of his Horses, he can use his move to add an additional Horse to any square on the board.

10. Promoting the Horse to Absolute Knight - OPTIONAL RULE
The Horse can be promoted to Absolute Knight. If a player moves the Horse to the seventh or eighth rank during his turn,
he can promote the Horse to Absolute Knight. Promotion of the Horse is optional. The Absolute Knight moves and captures
like a traditional Knight, but can no longer detach a Pawn from itself.

11. Promoting the Queen to Archbishop or Chancellor ( Queen + Horse = Archbishop or Chancellor ) - OPTIONAL RULE
While moving, the Queen may enter the square occupied by a friendly Horse. The horse does not necessarily have to be "empty",
it can contain a piece - be the Knight or the Royal Knight. Because the Queen, being the strongest piece, can throw off
a friendly Pawn or King next to it. However, it doesn't work the other way around - the Knight or Royal Knight cannot enter
the square occupied by the Queen, only the Horse can do so. After combining the Queen with the Horse, a new piece
is created - the Archbishop or the Chancellor. The Queen's entry into the square occupied by a friendly Horse must be from
the horizontal or vertical side, in the same way the Queen leaves the Archbishop or Chancellor. When the Queen leaves
the Archbishop or Chancellor, she must occupy a square adjacent to the piece she is leaving.
The Queen may leave the Archbishop or Chancellor when a player moves any of these pieces by moving like a knight, and then
the player may detach the Queen from the Archbishop or Chancellor. Once a player moves one of these pieces like a Bishop or a Rook,
the Queen cannot be detached. A player may also use his move to detach the Queen from the Archbishop or Chancellor
without first moving the piece. A player cannot detach the Queen from the Archbishop or Chancellor if he has made
a move in which he has captured an opponent's piece.
Variants of the Queen's promotion
In Trojan Chess, there are two variants of the Queen's promotion, namely she can be promoted to Archbishop or Chancellor:
- The Archbishop is a combination of a Knight and a Bishop
- The Chancellor is a combination of a Knight and a Rook

* When a Queen leave the Archbishop or Chancellor, it cannot capture enemy pieces.


Other variants of the King promotion:
In Trojan Chess, there are two possible variants of promoting the king to another piece, namely:
1. Horse + King = Royal Knight ( BASIC VARIANT )
Royal Knight - moves and captures just like a traditional Knight, but can also be put in check or checkmated.
When a Royal Knight is in check, he cannot move like a traditional Knight. During check, the Royal Knight can only
make a move just like a traditional King or a King can leave a Royal Knight.
2. Horse + King = Royal Unicorn
Royal Unicorn - a combination of the traditional Grasshopper and King pieces, and can also be put in check or checkmated.
When the Royal Unicorn is in check, it cannot move like a traditional Grasshopper. During check, the Royal Unicorn can only
make a move just as a traditional King or a King can leave the Royal Unicorn.


Trojan Chess30 - VARIANT OF THIRTY STARTING POSITIONS
Trojan Chess30 is a variant in which the chess pieces will be shuffled with only King, Rooks and Pawns remaining on original
starting squares as per normal chess to ensure normal castling. Thirty starting positions can be generated this way.  

Last revised by Piotr Smagacz.