2/1 game forcing (Two-over-one game forcing) is a bidding system in modern contract bridge, where a non-jump two-level response to a one-level opening bid commits a partnership to at least the game level. It is based on Standard American bidding and has largely superseded it; the principal difference is that a full opening bid is required for a response at the two level to an opening bid of one of a major. Thus, the response of 1NT to 1♥ or 1♠ opening is forcing or semi-forcing.