The Rat Pits' ability to produce quick cash attracted many local gamblers, ranging from ragged city tramps looking to earn a day's meal to wealthy businessmen and women there purely for sport. In the Pits, these gamblers would bet on their cats, who attempt to kill rats faster than their opponent.
The inhumane and underground nature of the Rat Pits made gamblers frowned upon by much of society. Many cats are killed in combat, leaving their owners penniless and often shirtless. This contributed to crime and poverty in cities such as Varrock, and the bars established in the Rat Pits only worsened the matter.
Players could not bet against the gamblers, and instead fought with another player. The gamblers, however, were willing to explain how the Rat Pits worked and were a point of interest to those on their first visit.