Kansas City refers to a form of lowball poker wherein the best possible hand is 7 – 5 – 4 – 3 – 2. This distinguishes it from California lowball in which the best hand is 5 – 4 – 3 – 2 – A. As in all forms of lowball, the aim is to make the lowest poker hand.
In Kansas City Lowball, Aces play high only, and straights and flushes count against the player. The combination of these two rules is what makes 7 – 5 – 4 – 3 – 2 the best hand.
We've seen the epithet “Kansas City” used to describe any poker variant with this hand ranking system. However, it has a more specific usage: Kansas City Lowball more properly refers to the five-card, single-draw, NL game that employs the hand ranking structure described above.