Some of the design elements are skeuomorphic throwbacks to traditional currencies. One design pattern among currencies is "person on front, place on back" - we

Some of the design elements are skeuomorphic throwbacks to traditional currencies. One design pattern among currencies is "person on front, place on back" - we didn't want Kong to be too geographically local so we picked the planets (Mercury, Venus, Mars, Luna, etc) for the places and the associated Roman pantheon. Romans used currency while Greeks famously didn't. (Lydians aside.)