Gin Rummy

Gin Rummy is the two-player card game where the whole contest is the shape of your own ten cards. Each turn you draw — from the face-down stock or the face-up discard — and throw one card away, working your hand into melds: three or four of a kind, or runs of three or more in one suit. Whatever fits no meld is deadwood, counted at face value with pictures at ten.

Knock when your deadwood is ten or less and the hands are compared: you score the difference, unless your opponent's count is as low as yours and the undercut bonus goes the other way. Knock with no deadwood at all and it is gin, worth a bonus and safe from the undercut. The board groups your melds for you and counts your deadwood as you draw, so the arithmetic never gets between you and the decision.