Stud where the lowest 5-card hand from 7 cards wins.
Aces are 1, and straights and flushes don't count, so the best hand is 5-4-3-2-A and pairs are bad. The bring-in is the highest door card (K is highest; on a tie, the ♠ pays), and from 4th street on, the player with the best low on board acts first. Example: starting with three cards 8 or lower, you complete an 8-or-better low by 7th street about 48% of the time. The R in HORSE.