Antichess (Losing Chess)

How the Rules Change

• The winner is whoever first loses every piece (except the king, which has no special protected status here) or has no legal move available (stalemate counts as a win in this variant too).
• Capturing is mandatory whenever it's available — if any legal capture exists, a player must play one of them rather than any non-capturing move.
• The king has no check or checkmate significance at all in most rule sets — it can be captured like any other piece.

History

Antichess (also widely known as "Losing Chess") has circulated as an informal variant for well over a century, and remains popular today as a standard variant option on major online chess platforms.

Why Play It

Completely inverting the objective forces a totally different kind of calculation — sacrificing material on purpose, and forcing your opponent into forced capture chains, becomes the whole game.