Chess rules can be found at https://en.wikipedia.org/wiki/Chess
This program support all moving rules including casting and en Passant. Chess must move according to rules, invalid move is not allowed. Moreover, a game is lose only when checkmate or resign, intentionally or unintentionally to place King in danger is prohibited. The program can detect checkmate automatically, notification will be generated once checkmate occur.
Extra feature(undo and step record) has been made.