As a move a player can do something called TM. This special move depends on the amount of material you have taken with the piece.
For eg a knight take a pawn. It uses TM. TMs use the material count for each piece so a pawn TM is 1. This allows the knight to move like a pawn for the next 5 moves.
But there’s a twist. Your opponent can also do something called HM. Same as TM, one of the pieces uses HM and it un-TMs the same opponent piece
Really bad chess!
https://www.chess.com/forum/view/chess960-chess-variants/really-bad-chess
The really best chess has many fairy pieces!