Patchanka is a chess variant played on a 10x10 board, invented by Jean-Louis Cazaux. It gathers pieces that appear in none of the author's other variants: most of them are compounds of two simpler pieces.
Each player commands 24 pieces: a King, 10 Pawns, 2 Soldiers, 2 Phoenixes, 2 Kirins, 2 Badgers, 2 Rams, a Bison, an Okapi and a Wildebeest. The Medusa, the strongest piece of the game, is not on the initial array and appears through promotion only.
Moves as in usual Chess, except that there is no castling in Patchanka.
Moves one square straight forward without capturing, or two squares from its starting position if the square it crosses is empty, and captures one square diagonally forward - as in usual Chess. Only its promotion differs.
An augmented Pawn. It captures one square diagonally forward like a Pawn, but moves without capturing either one square forward or one square sideways, left or right. It may also step two empty squares straight forward from any position on the board, not only from its starting square. The same piece is found in Zanzibar-Maasai Chess and in Bigorra. Betza: fsmWfceFfmnnD.
The next three pieces are the compounds of the oblique leapers - Knight (2,1), Camel (3,1) and Giraffe or Zaraffa (3,2), taken two at a time.
Leaps as a Knight or as a Camel. Betza: NC.
Leaps as a Knight or as a Giraffe. Betza: NZ.
Leaps as a Camel or as a Giraffe. Betza: CZ. It is worth about as much as a Rook would be on this board.
The next two come from Chu Shogi, and are compounds of the basic one- and two-square atoms.
Steps one square diagonally as a Ferz, or leaps two squares orthogonally as a Dabbaba. Betza: FD.
Steps one square orthogonally as a Wazir, or leaps two squares diagonally as an Alfil. Betza: WA.
And the last two are the grown-up versions of the previous two: FD becomes FFD, and WA becomes WWA. That is why a Kirin promotes to a Badger and a Phoenix to a Ram.
Rides diagonally as a Bishop, or leaps as a Dabbaba. Betza: BD, hence its name BaDger.
Rides orthogonally as a Rook, or leaps as an Alfil. Betza: RA, hence its name RAm.
Combines the powers of the Badger and the Ram, that is, the moves of the Queen plus the leaps of the Alfil and the Dabbaba. Betza: QAD. It is not on the initial array and only ever appears by promotion.
Several pieces promote on reaching the last rank. Promotion is immediate and compulsory, and the piece obtained is never a matter of choice:
Whenever a Pawn or a Soldier takes its double step and crosses a square attacked by an enemy Pawn or Soldier, that piece may capture it as if it had moved only one square. The capture must be played on the move immediately following the double step. Only a Pawn or a Soldier may capture en passant.
Note that the Soldier keeps its double step everywhere on the board, so an en passant capture may happen anywhere - including by a Pawn that has not moved yet.
There is no castling. Checkmate, stalemate and the other end-of-game rules are those of orthodox chess. White plays first.
The values estimated by the author's interactive diagram: Pawn 0.8, Soldier 1, Phoenix 2.9, Kirin 3.1, Bison 5, Okapi 5.3, Badger 5.3, Wildebeest 5.5, Ram 6.3, Medusa 10.2.