Integration is how we describe the incorporation of source materials into MCM's setting. Individual settings are called themelists, and you can view a list of them by typing -> +themelist <- on the MUSH.
When a theme is integrated, it is brought permanently into the Multiverse in a process called Unification. Unification transports at minimum all of the themelist's locations of significance, though more frequently the entire theme's world comes with it. While this is usually not physically observed or experienced, the physical appearance of a unified world is as if it was unfurled into a sheet and stitched in to the planet-- itself composed of many other unfurled and stitched in worlds. Alternate planes and dimensions attached to inherently Multiversal themes come with them, and are likewise accessible as they would be normally. In most cases characters unify with their theme, but occasionally something goes wrong and a newly-unified person finds themselves scattered to some other corner of the Multiverse without any knowledge of where their world actually is.
All characters with an integrated theme have their world physically present in the Multiverse, even if they don't know where it is.
All themes are automatically linked to a central feature of our setting: the warpgate network. Warpgates begin to open within a newly unified world almost immediately, and they're what they sound like: Locations where it's possible to rapidly (but not instantly) travel between connecting warpgates. All worlds end up with as many warpgates as public points of interest, minimally as common as major airports.
Natural warpgates are impossible to destroy, but artificial warpgates can be constructed and destroyed.
For more details on Warpgates and the history surrounding them, see their page here.
For reasons unknown, the concept of a language barrier only loosely exists in the Multiverse. Everyone can inherently understand one another to a minimum degree whether they speak a common language or not; their language isn't changed, and listeners can recognize that, they just understand with acceptable clarity. This extends more loosely to common written language, but written language translates less consistently than spoken language.
Universal translation isn't perfect and doesn't extend to secret, code, or dead languages. If it's narratively important for a language not to translate, it doesn't have to. Player characters are required to know at least one language that allows them to communicate with other player characters, however.
In the interest of avoiding primacy conflicts, MCM defines the spiritual disposition of all settings. In brief: All sapient life has a soul, there is some life-after-death but only worlds that have materially visitable afterlives are sure what it looks like (for them), and souls can't be destroyed though they can be put into a state of irretrievability for the purposes of the materially living.
In addition, while deities from source materials that have them do have the powers they'd be expected to within their own worlds, their metaphorical mod privileges are strictly local. That includes their dominion not extending properly to people from outside; Zeus might well be able to smite his local Percy Jackson out of hand, but Kratos or even an alternate universe Percy Jackson wouldn't fall under his divine privilege in the same way.
Updated as of November 2025.