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This page is written by the game's inventor, Paul Keres.

Chess++

Introduction
Setup
Pieces
Rules
Playing Tips
Computer Play
Equipment
Sample Game
Contact

Introduction

Extended chess' main characteristic is the increased mobility of some pieces and the reduction of others. Pawns, bishops, knights, queen and king have modified movements. This idea came by influence of observing the changes that traditional chess suffered in the XVth century. In extended ches pawns are used as infantry in an army in campaign, for they can advance or retreat, make flank movements and again retreat or advance at will. The bishops can change the color according with the strategic necessities, and can also make turns in their diagonal movement. The knights have the option to make two leaps, and the king in view of such a dynamic environment has the extra mobility of a single knight leap. Also as the dynamics of a chess++ game are increased the need of castling is of no use. In general the movement of the pieces follow the standard idea of traditional chess, so the bishops move in a diagonal way, the knights make a change of diagonals and the pawns move step by step and take in diagonal.

Setup

Standard setup

Pieces

  1. Pawns can move one square forward, backward and to the sides, like a +. Can take in diagonal at the four next squares, like an X. Can move two squares forward at the beginning of the game as in standard chess.
  2. Bishops move in diagonal a maximum range of 4 squares. Can leap over pieces. Can turn the direction of a diagonal move at an available free square. If they leap, a possible turn has to wait until they land on the board. Can change the color of square by an intervening move to the sides, backward or forward at a free square. Can only take in a diagonal move.
  3. Knights can make 1 or 2 leaps passing by an empty square in the 1st leap. Can check the enemy king only in the range of a single knight leap, as in traditional chess.
  4. The King moves a square in every direction as traditional chess, and has also the move of single knight leap.
  5. The Queen has a maximum range of 4 squares laterally, forward, backward or in diagonal (as in traditional chess, but only 4 squares).
  6. Rooks move as in traditional chess.

Rules

The rules concerning the right to move and repetition of moves are identical to traditional chess, but:
  1. There is no castling and no en passant.
  2. Checkmate, stalemate and a bare opponent king count as a win.

Playing Tips

A series of games played under the Chess++ rules will show the need of deep visualization because of the extended movement of the pieces. Constant planning of possible moves of the knights is an example, for the objectives are widened.

Pawns could be still considered the soul of the game for his dynamic movement. For instance a pawn in c4 could have the moves: c4-c5, c4-c3, c4-b4, c4-d4 A pawn in c4 can take at: cxb5, cxd5, cxb3 and cxd3 The 2-square move of pawns at the beginning of a game is like in standard chess.

Bishops have many possibilities of play. For example in a empty board a bishop on d4 could have the move: d4-e5-f6-g7
or turn in e7 this way: d4-e5-f6-e7
or turn in e5: d4-e5-d6-c7
or make two turns: d4-e5-d6-e7
or a go down and turn at f2: d4-e3-f2-g3

In case there is an obstacle on his way, the bishop could simply jump it and then choose to make a turn.
For instance a bishop on d4 leaps over a piece on e5: d4-f6-g7
or with a turn after the leap: d4-f6-e7
A change of color with a bishop on d4 would be: d4-e4, d4-d5,d4-d3, d4-c4.

Knights have been always an enigmatic piece and in extended chess the possibilities increase. For example a knight on e1 could go to d3 in one leap or e5 in two. Or have the path e1-d3-f4 or e1-c2-d4, or simply e1-c2. The result of this being that the color of square can be the same or different color according to the leaps. In case of a check with the knight on e1 and a king on e5, the knight will have to get closer to the king, to d3+ or f3+. So from a distance of two leaps he has no check.

The King is provided with the move of knight, so a King on e5 could have the moves: e5-e6, e5-e4, e5-d5, e5-f5 or have the single move of a knight: e5- (f7, g6, g4, f3, d3, c4, c6, d7)

The Queen has remained almost the same but his range is decreased. A Queen on d4 could have the path: d4-d5-d6-d7-d8 or: d4-d3-d2-d1 or diagonally d4-e5-f6-g7 etc.

Equipment

Chess++ uses the same 8x8 checkered board and pieces of traditional chess.

Sample Games

Here are two games played by the Extended Chess rules. Careful examination will show that the games are not played without mistakes, nevertheless will show the use and movement of pieces. The games are in PGN format and commented in a rather repetitive way to clarify the moves. Winboard can be used to see them with the option "test legality" turned off.

[Event "Used Car Match"]
[Date "2003.09.17"]
[Round "1"]
[White "Salesman"]
[Black "Singer"]
[Result "0-1"]
rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR
1. h4 g5 2. hxg5 Bf8xg5 {Taking via the open path of g7.}
3. f4 {A protected pawn at 2 leaps from the knight on g1.}
3... Bf6 4. Nf3 e5 5. fxe5 Nb8xe5 {A 2 leap move passing by the empty square c6.}
6. Nxe5 Bxe5 7. d4 Bg7 8. e4 f5 9. exf5 Ng8xf5 {Via e7 or h6, both empty squares.}
10. Bd3 Nf5xh1 {Passing by g3 in 2 leaps.} 11. g2xh1 Qe7+ 12. Na3 d5+ 13. Bf4 Be6 14. Bxc7 {c7 was protected for the king in a knightly manner, but was attacked twice by the a3 knight and the f4 bishop.}
14... Be6f6 {The bishop changes of square color and now attacks c7 square that its within its 4-squares range} 15. Bc7xf6 {Taking via the open path e5.} 15... Ke8xf6+ {A knightly move by the king.}
16. Ke1f3 Raf8 17. Na3xa7 {Taking the unprotected pawn in two leaps.}
17... Kf6d7+ 18. Kg3 Qg5+ 19. Qg4+ Qxg4+ 20. Kxg4 h5+ 21. Kh4 h5g5+ {A lateral move and the pawn is protected by the bishop bya f6 or h6.}
22. Kg4 Rh4+ 23. Kg3 Bg7f4+ {A twisted check the bishop passed by the empty square e5.}
24. Kg2 Rh2+ 25. Kf1 Rxh1+ 26. Kg2 Rxa1 27. Bb5+ Kd7b6 28. a4 g5h5
29. b4 h4 30. a5+ Kb6a8 31. a6 {The b7 pawn is pinned for if it closes the bishops path to the king.}
31... h3+ 32. Kf3 Bd6+ {Winning the knight for the black bishops has a path to it.}
33. Kf3g5 Bd6xa7 {Taking via b8.}
34. Kg5xh3 Rxa6 35. Bxa6 bxa6 36. c3 a6b6 37. Kh4 b6c6 38. Kg5 Ka8c7 39.
Kg4 d5d6 40. Kg5 c5 41. bxc5 dxc5 42. d5 Kc7xd5 43. c4+ Ke5 44. c4d4+
Ba7xd4 {Black wins for white has no pieces.} 0-1

[Event "Used Car Match"]
[Date "2003.09.17"]
[Round "2"]
[White "Salesman"]
[Black "Singer"]
[Result "0-1"]
rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR
1. e4 e5 2. Nf3 Nc6 3. Nf3xc6 {Taking in 2 moves and passing by the empty square d4.}
3... bxc6 4. Na3 Nf6 5. d4 d6 6. Bd3 exd4 7. Na3xd4 {Passing by b5.}
7... g6 8. g4 h5 9. g4h4 {A lateral move.}
9... Bg7 10. Rg1 Bg7xd4 {The knight was in the 4 squares range of the bishop that jumps above his own knigth.}
11. Bc1xd4 {Also this bishop was in the 4 squares range that turned in the e3 square.}
11... Nf6xh2 {A 2 leap move by the knight passing by g3.}
12. Rg2 { To avoid been taked by the knight in 2 leaps. }
12... Ng4 13. Rg1 Nh2 14. Ke1g2 Nh2xg1 {White decides it's OK and the black knight takes passing by f3.}
15. Kxg1 Rg8 16. Kg1h3 {A knightly move by the king.}
16... Bb7 17. f4 c5 18. Be3 c4 {The pawn is protected by Bb7 passing either at a6 or d5.}
19. Be2 f5 20. Qd4 Qe7 { The queen has a 4 squares range and now aims at e4.}
21. exf5 gxf5 22. Rg1 Kf7 23. Rxg8 Rxg8 24. Bxc4+ Bb7xc4 25. Qxc4+ d6e6 {A lateral pawn move.}
26. Bc5 Qf6 27. Bxa7 Rg4 28. Ba7xc7 {Taking via the open paths of b8 or b6.}
28... Qxh4# {The white king is certainly in the 4 squares range of the queen.}
{Black mates} 0-1

Both games could be seen also online on a dynamic board in the Journal of SchemingMind, a correspondence chess website. A short fictional tale about the variation is also included. The link is: http://www.schemingmind.com/journalarticle.aspx?article_id=8&page=1