So the “Aztec” (Mixtec Pueblo culture) had two major calendars The Tonalpohualli (count of days or days count) and The Xiuhpohualli ( year count or fire count). The Tonalpohualli is a spiritual calendar used for ceremonies and augury, it consists of 20 signs each given a thirteen day week. I’ve heard it speculated that it has something to do with the observable time that a human takes to gestate during pregnancy, but that’s pure theory. The Xiuhpohualli is a 360 day count calendar with five extra days added to the end of the year (which were considered very unlucky). It was divided into 18 months that ran through the 20 day signs that the Spanish called a Veintena. This was used for feasts, holidays, and the planning of agriculture or war during the two major seasons (wet season and dry season). The two calendars would align every 52 years that culminated into a huge celebration called Toxhiuhmolpilia (New Fire Ceremony).
I hope the nightmare fuel is enough to get Megaman built before 2040.