At the beginning of a campaign of Warlords of the Moon, the Player Characters are assumed to be strangers to the Moon who arrive from Earth. This not only aligns with Sword & Planet genre tropes but also allows players to discover the lunar realms through their characters’ eyes. To emphasize the peculiarities of Warlords of the Moon, we suggest that starting characters are humans, or possibly terrestrial cats, and that lunarians, lunarian mutants, batkin, selenites, and robots are reserved for new characters joining the party after the beginning of the campaign.
How the PCs arrive on the Moon is a matter of what best suits your campaign. Here are some alternatives to consider:
Amazing vessel. The year is 1586, and the Danish astronomer Tycho Brahe has constructed a wondrous ship in which he wants the adventurers to travel to the Moon to map its lands and establish contact with its potentates for the benefit of King Frederick II.
Rocket. The year is 1572, and Conrad Haas, the arsenal master of the Holy Roman Emperor Ferdinand I, is a prodigious engineer and a pioneer of rocket propulsion who has made designs for manned multi-stage rockets using liquid fuel. Now he needs a crew for a trip to the moon!
Vacuum airship. In 1670, the Italian Jesuit priest Francesco Lana de Terzi constructs an airship carried by vacuum balloons. He recruits the Player Characters to spread the doctrine of the Catholic Church to the inhabitants of the moon.

Space Race. The players assume the roles of the first US astronauts landing on the Moon in 1969, or perhaps they come from a timeline in which a crew of Soviet cosmonauts got there first. The world they land on turns out to be astonishingly different from that which has been observed through telescopes. Batkin warriors open fire on the lunar lander, damaging it so that it can’t lift off for the journey home, and on the radio, only strange voices whispering in unknown languages can be heard.
Dream-quest. The player characters are dream avatars of sleeping Earth people. In their dreams, they are manifested as adventurers on the Moon. Whenever a player cannot attend a game session, their character is gone because the dreamer is awake during that time.
Portal. Beneath the streets of 19th-century London, there is a mysterious portal that leads to a corresponding place beneath Issum. A secret society controls the portal and recruits the adventurers to go through it to search for a previous expedition that disappeared under mysterious circumstances.
Teleportation. The adventurers may be teleported to the surface of the Moon through a mysterious gate at the lowest level of some ancient dungeon or through some sort of magical mishap.