In addition to classic chess, RPB Chessboard supports games played according to several alternative game rules. Those supported chess game variants are listed below.


Chess960, also known as Fischer Random Chess is very similar to classic chess (same board, same pieces, same rules), but the initial position of the pieces is randomized. See this page for more information.

[SetUp "1"]
[FEN "qbnnrkbr/pppppppp/8/8/8/8/PPPPPPPP/QBNNRKBR w KQkq - 0 1"]
[Variant "Chess960"]


1.f4 Nd6 2.Bc5 Nc6 3.O-O O-O-O *

PGN-encoded Chess960 games must have the [Variant "Chess960"] header ([Variant "Fischerandom"] is also supported). For this variant, the headers [SetUp "1"] and [FEN "..."] describing the initial position are also mandatory.


In antichess (also known as losing chess, giveaway chess, suicide chess…), the objective of each player is to lose all their pieces. Capture is mandatory when possible. See this page for more information.

[Variant "Antichess"]

1.d3 ?? g5 2.Bxg5 Bg7 3.Bxe7 Bxb2 4.Bxd8 Bxa1 5.Bxc7 Bc3 6.Bxb8 Rxb8 7.Nxc3 d5 8.Nxd5 Nf6 9.Nxf6 Rg8 10.Nxe8 Rxg2 11.Bxg2 f6 12.Bxb7 Rxb7 13.Nxf6 Rb8 14.Nxh7 Rb1 15.Qxb1 Bb7 16.Qxb7 a6 17.Qxa6# 0-1

PGN-encoded antichess games must have the [Variant "Antichess"] header.

Horde chess

In horde chess, White has only a horde of pawns (36 paws by default), while Black has the regular pieceset. White’s objective is to checkmate Black, while Black’s objective is to capture all white pieces. See this page for more information.

[Variant "Horde"]


1.d5 d6 2.d4 a5 3.d3 axb4 4.axb4 c6 5.b6 Nd7 6.a5 dxc5 7.dxc5 Nxc5 8.bxc5 Rxa5 9.b4 Ra6 10.d4 Bxf5 11.gxf5 Qa8 12.dxc6 bxc6 13.d5 cxd5 14.exd5 Nf6 15.gxf6 gxf6 16.b5 Ra5 17.b4 Rxa2 18.bxa2 Qxa2 19.b7 Qa7 20.c6 e6 21.c5 Bxc5 22.bxc5 O-O 23.fxe6 fxe6 24.b6 Qxa1 25.c7 Qxc3 26.b8=Q Qxc5 27.dxe6 Qd6 28.Qb7 Qxe6 29.e4 Qd7 30.Qd5+ Qxd5 31.exd5 1-0

PGN-encoded horde chess games must have the [Variant "Horde"] header.

No king variants

[SetUp "1"]
[FEN "8/ppp5/8/PPP5/8/8/8/8 w - - 0 1"]
[Variant "No king"]

{[#] Forced passage with 3 pawns vs. 3 pawns}

1.b6 cxb6 2.a6 bxa6 3.c6 +- *

PGN-encoded games with the [Variant "No king"] header correspond to games (or part of games) played according to the classic chess rules, but with no king on the board. Obviously, this is not a playable chess game variant, but it allows to illustrate chess manoeuvres without the need of introducing kings when they are not part of the manoeuvre.

[Variant "White king only"] and [Variant "Black king only"] are also supported, respectively for illustrative games without the black king and without the white king.