Lots of chess variants have been made since the first man walks the earth, and this is just another one. Why not :-)?
Denial (hard/strong version)
Denial is a special move that allows a player to deny one movement of another player, the player with the denial right can deny one move at any time, the opposing player that have the move denied must undo the last move and perform a different one (with the same piece or any other). After the player with denial right uses this special movement the opposing player gain the denial right.
After any player denies a movement, that player next movement cannot be denied, in other words, when a player denies a movement the opponent must undo his last move and perform a new one, then the game resumes but the first move of the player that just used the denial cannot be denied, after that the denial rules apply as normal.
Black pieces starts the game with the denial right.
Exceptions: It´s useless to deny knight normal moves, since there are two paths for a knight to take for every of it´s movements. Using normal chess movements the knights are immune to denial.
Denial (soft/weak version)
Since denial is very strong in many end game scenarios the optional rule is that a king's move can never be denied(including castling).
After the third denial in a given game, the player with the denial right can call a draw at any time unless it´s king is in check.