This is a basic chess program written in python, it allows all basic legal moves and some special moves. moves that this program does not support: En passant and pawn promotion to a piece other than Queen.

1. All pieces can only move to squares they are allowed to - which are highlighted red for a selected piece.
2. A piece cannot move into a square that is occupied by a piece of the same color.
3. A pawn is allowed to move 2 squares on its first move, after that, the pawn can only move forward 1 square.
4. A pawn can move diagnally only when there is a piece of the opposite color to be taken.
5. Pawn promotes to a queen when it reaches the end of the board.
6. The King's square is highlighted red when the King is in check.
7. The King cannot castle after moving.

1. Whether or not a piece can block a check by moving in front of the king.
2. Whether or not the squares between a king and a rook are attacked before castle (unless the square is the king's destination square for castling).
3. Whether or not a piece's movement would put the king in check.