Inspired by IWantCheckmate playing Drawback Chess on YouTube.
Enhanced Chess is a chess variant, built with Rust. The board is a slightly modified fork of gchessboard.
Since enhancements can sometimes create a check or checkmate that the normal rules of chess wouldn't allow, this is a king capture variant. This also means a king can be captured "en passant" on its starting square right after castling, and can move or castle out of, through and/or into check. The board only warns you about checks that come from the regular rules of chess.

Glossary

Ply
One piece move by a player.
Half-turn
All the plies a player makes before play passes to the other color. In standard chess this is always a single ply, but some enhancements let a player make more than one.

Enhancements

Pawns

  • Nepotism: Pawns can promote to a king
  • Retreat: Pawns can move backwards
  • Sidestep: Pawns can move sideways
  • Agile Infantry: Pawns can move diagonally
  • Fast Infantry: Pawns can always double push
  • Spearmen: Pawns can capture in front
  • Opportunist: Pawns can promote on the seventh rank

Knights

  • Nimble Cavalry: Knights can move one square like a king
  • Fast Cavalry: Knights can move twice in a row, as long as the first move is not a capture

Bishops

  • Cartesian Clergy: Bishops can move one square orthogonally
  • Mounted Clergy: Bishops can move like a knight
  • Diocese: Bishops can jump one friendly piece
  • Missionaries: Bishops can jump one enemy piece
  • Universal Religion: Bishops can jump one piece of any color

Rooks

  • Skewed Rampart: Rooks can move one square diagonally
  • Horse Carriage: Rooks can move like a knight
  • Paved Way: Rooks can jump one friendly piece
  • Embassy: Rooks can jump one enemy piece
  • Trade Route: Rooks can jump one piece of any color

Queens

  • Amazon Queen: Queens can move like a knight
  • Beloved Ruler: Queens can jump one friendly piece
  • Diplomatic Immunity: Queens can jump one enemy piece
  • Dynastic Marriage: Queens can jump one piece of any color

Kings

  • Yield to the Prince: Kings can jump one piece orthogonally
  • Yield to the King: Kings can jump one piece in any direction
  • Caravan: Kings can castle, even vertically, as long as it is on the same rank/file as a rook
  • Cortege: Kings can castle, even vertically, as long as it is on the same rank/file as a rook or queen

Player

  • Predatory Pact: Draws are a win for the player
  • Laziness: Player can pass their turn
  • Permutation: Player can swap two major or minor pieces
  • Load Shedding: Player can sacrifice a major or minor piece to move once more
  • High Ground: Player can move a major or minor piece a second time if it lands in one of the middle 4 squares
  • Second Wind: Player can do a second non capturing move with a piece that just captured
  • Ambidextrous: Player can move one major or minor piece from the first 4 files and one major or minor piece from the last 4 files consecutively
  • Encore: Player can play one more ply