The name registry behind Cauldron2D.Worlds.world_name/1:
{:via, Cauldron2D.Worlds.OnDemand, id} resolves to world id, starting the
world when it is not running. An id no world is registered for resolves to :undefined.
{:on, node, id} (Cauldron2D.Worlds.world_name/2) resolves to world id of a
connected node the same way, started there; :undefined when the node cannot be
reached.