Rat Things, also known as semi-autonomous guard units, were built to be the guard force for the 'Mr. Lee's Greater Hong Kong' franchise of city-states. Rat Things were invented by Mr. Ng, the owner and administrator of Ng Security Industries, who was severely handicapped after a helicopter accident in Vietnam and voluntarily had himself turned into a cybernetic organism to regain his lost mobility. However, they escaped and spread throughout the post-apocalyptic United States, killing people indiscriminately and wreaking extreme havoc and destruction wherever they went.