Symmetric 8x8 chess

[Admin]

Pawns can move in 2 direction (laterally) and capture in 3 directions (diagonally) pawns has to move in at least one direction towards one of your opponents sides.

https://www.omnichess.club/variant/7f73f19e-b13d-4854-8df9-d7d0e272091b

Yellow: where white pawns can capture
dark green: where white pawns can go without capturing.

Pawns can be promoted on the squared behind the opponents pawns.

Promotion on light squares is compulsory (to queen xor centaur)

If you reach a dark promotion square from a square where you cannot promote you can promote to bishop, knight xor rook.

If you reach a dark promotion square from another promotion square you can promote to knightrider, archbishop xor chancellor.

 

[Admin]

The centaur
It moves like king + knight

A centaur can force mate against a bishop.

A centaur can force mate against 2 knights.

A centaur and a knight can force mate against a rook.

Allowing promotion to centaur would make promotion to other non-queen pieces the best move less often. One way to maybe resolve this is to have double promotion (bishop or knight placed on the position the pawn had prior to promotion) if you do not promote to queen or centaur.

 

[Admin]

Fairy Stockfish versions
While i did get a version working with fairy stockfish i did not find any way to make the promotion system like i wanted.

[8x8symmetricw:chess]
maxRank = 8
maxFile = 8
centaur = c
archbishop = a
chancellor = h
amazon = w
nmoverule = 50
customPiece1 = p:fmWrmWfcFrbcF
customPiece2 = f:fmWrmWfcFrbcF
promotionRegionWhite = d8 e8 e7 f7 f6 g6 g5 h5 h4 f8 g8 g7 h7 h6
promotionRegionBlack = a5 a4 b4 b3 c3 c2 d2 d1 e1 a3 a2 b2 b1 c1
promotionPawnTypes = p
promotionPieceTypes = acqhf
promotedPieceType = f:w
mandatoryPiecePromotion = true
stalemateValue = win
startFen = 2prbbnk/3pnqrn/P3pcqb/RP3pnb/BNP3pr/BQCP3p/NRQNP3/KNBBRP

https://mega.nz/folder/DAxkmZ4B#pNvdjEw_I6M7q3P72vLZ-Q

 

[Admin]

Fairy stockfish test 100 million nodes/move
No straight forward win/draw for either player (not even close):

b5c5 c8c7 e2e3 h3g3 a6b6 c7b6 c5b6 d7d6 a5a7 f5e5 b4c6 d8c8 a2b4 e8d7 f1f2 g3f2 e3f2 g5f3 d2f3 g4f3 b1d2 g6g2 d2f1 e7f5 f1e3 g2h2 c2b1 h6g5 b3a2 g5f4 c6a5 g8e7 e3f5 f6f5 c1f4 f5f4 a4d7 e6d7 a7d7 c8a8 d7a7 a8a7 b6a7 f4g2 d1b3 g7g5 a5c6 f7g7 b1c1 e7c6 b4c6 h5e8 a7b7 h2h3 b3a4 g2f4 b2b5 h7f6 a3b2 g5g2 a4c2 g2f2 d3e3 f2c2 c3c2 f4e2 e1e2 f3e2 c2d2 e8h5 e3f3 h3f3 d2f3 h5f3 c6e5 d6e5 b2e5 g7e7 b7c7 h4e4 a2a5 e2e1h c1e1 e4e1 a5e1 h8g8 e1c3 f3g4 e5f6 e7c7 c3c2 f8g7 c2g6 c7a7 a1b2 a7f2 b2b3 f2e3 b3a4 g4d1 a4b4 e3b3 b4c5 b3a3 c5d4 a3d6 d4e3 d6e6 e3d2 e6e2 d2c1 e2c4 c1d1 c4f1 d1c2 f1c4 c2d2 c4f4 d2e2 f4c4 e2e3 c4c1 e3d4 c1f4 d4d5 f4f3 d5c5 f3f2 c5b4 f2d2 b4b3 d2d1 b3b2 d1d2 b2b3 d2d1 b3a3 d1d6 a3a4 d6a6 a4b4 a6d6 b5c5 d6b6 b4c4 b6a6 c4d5 a6b7 d5d4 b7b4 d4d3 b4b1 c5c2 b1f1 d3e4 f1h1 e4d4 h1a1 d4e3 a1a7 e3f3 a7b7 f3g3 b7b8 g3h3 b8b3 f6c3 b3f7 g6g7 f7g7 c3g7 g8g7 c2f2 g7h6 h3g4 h6g6 f2f1 g6h7 g4g5 h7g7 f1f2 g7h7 g5f6 h7h8 f6f7 h8h7 f2h2

b5c5 g4f4 c4d4 c8c7 e2f2 d7d6 d1h5 f6h5 d3e3 d6c5 a5c5 e8a4 c3a4 e6d6 c5a5 g8f6 b1c3 f7b3 b2b3 f4e3 f2e3 f6d7 c3e2 f5e5 e3e4 h7f6 d4e5 d6e5 a2c3 c7c6 a6b6 h3g3 e2g1 h5g4 d2f3 h4h5 f3g5 h6g5 c1g5 g6g5 g1f3 g5g6 a3b2 e5d5 f3d4 h5h2 c2c1 f6e4 c3e4 d5e4 d4c6 e7c6 c1c6 d7f6 a5a8 h2d2 a4c3 h8g8 b3a3 d2d6 a8d8 d6d8 a3a8 d8a8 c6a8 g7e7 c3c4 e7e8 a8a2 g6f7 b4c6 f6d7 e1d1 e4e3 a1b1 g8h7 a2a7 f7c4 a7d7 e8e7 c6e7 c4e4 b1a1 f8e7 d1d5 h7h6 d7c6 e4g6 c6c3 g6f7 c3c6 f7g6 c6c3 e7f6 c3b4 g3g2 d5d6 g4e5 d6f6 g6f6 b2e5 f6e5 a1b1 h6h5 b4f8 e3d3 f8f7 h5g5 f7g8 g5f4 g8f8 f4e3 f8h6 e3d4 h6d2 d4c4 d2a2 c4b4 a2d2 d3c3q d2c3 b4c3 f1g1 e5b5 b1a1 b5b2

b5c5 g4f4 c4d4 c8c7 e2f2 d7d6 c5d6 c7d6 a4e8 f7e8 d1h5 h4h5 c3e2 f5e5 d4e4 d6c6 b1c3 e6d6 d3e3 h3g3 f1g1 g5e6 c2d1 d8b8 a6a7 b8b7 b3c2 e7c8 d2c4 c8a7 f2g3 f4g3 e1f1 f6g4 b4d3 a7b5 c2a4 b5a3 a4a3 g7c7 b2b7 c7b7 a5a8 e8d7 c4a5 b7c7 a5c4 d6d5 e2g3 g4g3 d3e5 g6g7 f1f8 h7f8 e5d7 d5c4 d7f8 e6f8 e4f4 c7d7 d1a4 g3e2 f4g4 h5h4 a3f8 e2d3 f8f5 h4g4 a8g8 h8g8 a4a8 g7f8 f5e6 d7f7 e6g4 h6g7 a8f8 f7f8 g4e6 f8f7 e6c8 g8h7 c8h3 g7h6 h3h2 c6c5 e3f3 d3c1 a2c1 c4b4h h2b2 h6g7 c1b3 g7c3 b2c3 b4a4 a1b1 a4c3 b1b2 c3d3 b2a2 c5c4 g1h1 c4b3f a2b1 d3d1

b5c5 f5e5 e2e3 g5f3 d2f3 g4f3 e3e4 f3e4 d3e4 h5d1 c2d1 h4e4 e1e4 f6e4 c3e4 g6e4 b3h3 g7g1 b2g2 g1g2 f1g2 f7g6 d1c2 e4e1 a2c3 e1g1 c5c6 d7c6 a5e5 e7f5 c3e2 g1g2 h3g2 g6g2 e5e6 h6c1 a3c1 f8g7 c1b2 e8d7 b4c6 d7e6 c6d8 f5e3 c2c1 e3c4 b2g7 g2g7 b1c3 e6d5 a1a2 g7g2 a2a1 g2g7 a4b3 g8f6 e2f4 c4a5 b3c2 a5b3 c2b3 d5b3 c1e3 f6g4 e3e8 g7g8 e8e7 g8g7 a1b2 g7e7 f4g6 h8g7 g6e7 b3e6 d8e6 g7f6 e7c8 f6e6 c8a7 e6d7 b2b3 g4e5 a6b6 e5c6 a7b5 h7g5 b3a4 g5f3 c3d5 d7c8 d5b4 c8b7 b4c6 b7c6 a4a5 f3d2 a5a6 d2f3 b6b7 c6d7 a6b6 f3d2 b5c3 d2b3 c3b1 b3d4 b1d2 d4e6 d2b1 d7e8 b1c3 e6d8 b7c7 d8e6 c3e4 e8d7 e4f6 d7c8 c7d7 c8d8 b6c6 e6d4 c6d5 d4b5 d5e5 d8e7 e5d5 e7d8 d5e6 b5d4 e6d6 d4f5 d6e5 f5g7 f6h5 g7f5 h5f4 d8d7 e5f5 d7c6 f5e6 c6c5 f4e2 c5b6 e2d4 b6c5 d4f5 c5b5 f5g7 b5c4 e6f5 c4d3 g7e8 d3c2 e8f6 c2b3 f5e4 b3a4 e4d5 a4b3 d5c5 b3c3 f6g4 c3d3 c5d5 d3e2 d5e4 e2d2 g4e5 d2e2 e5f3 e2f2 f3d4 f2g2 d4e2 g2f2 e2d4 f2g2 e4e3 g2g3 d4e2 g3g4 e3e4 g4g5 e4e5 g5g4 e5e4 g4g5 e2d4 g5g4 d4f5 g4g5 e4e5 g5g6 e5f4 g6f7 f4e5 f7g6 f5d6 g6g5 d6f7 g5g4 e5e4 g4g3 f7e5 g3g2 e5d3 g2g3 d3e5 g3g2 e4f4 g2f2 e5c4 f2e2 c4e5 e2f2 e5c6 f2e2 f4e4 e2e1 e4e3 e1f1 c6d4 f1g2 d4f3 g2g3 f3h2 g3h2

b5c5 g4f4 a6b6 f5e5 f1f2 c8b8 e2e3 h5d1 c2d1 d7c7 b6c7 b8c7 c4d4 g6h5 c3e2 e7g6 b4c6 e8c6 a4c6 e5d5 c6a4 g8e7 b1c3 e7c6 a4c6 d5c6 d2c4 e6e5 a2b4 e5d5 e3f4 d5c4 d3c4 d8e8 f4g5q h6g5 c1e3 f6d7 c5d5 c6b6 a5a4 g6f4 e2d2 f4g2 e3g5 e8e1 d2e1 h7g5 e1d3 g5f3 b4c6 h3g3 a3f8 f7f8 f2g3 g7g3 d3f2 g3h3 f2g2 h3h1 b2f2 c7b7 g2g3 f8h6 g3h5 h6h5 d1h1 h4h1 c3b1 f3d4 c6d4 h5e5 c4c5 d7c5 b3f3 h1g1 f3f8 h8h7 f2f3 g1g7 f3h3 h7g6 b1c3 g7h7 a4a2 h7h3 a2g2 e5g3 f8g8 g6f6 g2g3 h3g3 g8g3 b6a6 g3f2 f6e5 f2e3 e5f6 d5e5 f6f7 e5e6 c5e6 e3e6 f7f8 e6b6 f8f7 b6b7 f7f6 b7a6 f6e5 c3e2 e5e4 a6e6 e4d3 e6b3 d3d2 b3c3 d2d1 c3c1