It's clear from the start that BREAK!!’s rules were written around the Outer World as a setting. The reality of its fiction is intertwined around and informed by the game’s mechanics. This was mainly in hopes that people could get a feel for the place while reading the book, so that it would be easy to jump in and make it their own while playing. That said if you really want to use your own world with BREAK!!’s rules, it’s not as difficult as it might first seem to be, it just requires a bit of extra work and consideration on your part.
Naturally creating something like this can be a deeply personal process so you can (and should) do it in a way that you feel most comfortable with. However, this entry can provide you with some guidelines to get you started and let you know all the things you’ll probably need to flesh out your world and get it ready for players.
Conceptualize your setting
It's a good idea to have your setting concept worked out to help inform your other decisions. Is it an oceanic world of piracy and treasure hunting? Something based on your favorite show/comic/novel but with your own twists? Your own variant of Outer World itself? Figure out the place, tone and themes, and it’ll help narrow your future decisions.
It also might help to decide if you want to make any tweaks or changes to the rules for your setting. For example, do you want a gloomy, foreboding world? The Dungeon Attrition rules in this Options Menu entry could be just the thing.
All that said, you don’t need to have every detail figured out right away. Even just a vague idea might be enough to get started with.
Create an Adventure Map
While you won’t need a whole world map to start a saga, you’re going to want to have at least one spot figured out so the characters have a place to run around in.
The guide for creating Adventure Maps in the BREAK!! rulebook should work for you here, but just keep your own setting and its themes in consideration rather than Outer World’s.
If you start out with a single Adventure Map, you build the world slowly by figuring out what other places you can get to from there, and fleshing those out as you need to. You can make building out your world a gradual process rather than one big effort, which keeps you from exhausting yourself with prep time.
Decide on character options
If the standard Calling, Species, Quirk and gear options for BREAK!! fit into the world you are creating, you don’t need to worry about this part.
That said, you may want to consider limiting or altering these options if your setting concept calls for it.
For example, you may want to re-flavor magic Callings to tie into the otherworldly force that dominates your homemade fantasy universe. If the setting is a strange, alien landscape you may want to limit the available species to modified versions of Tenebrate, Prometheans, Bio-Mechanoids, and Goblins. Running in a different era of the Outer World might mean some of the rare relics and gadgets in the main book are more common and available for players, and so forth.
Make a Histories Table
Once you have your setting thought out and an adventure map to work with, you’re going to need a history table.
The easiest way to do this is to take an existing one from the rulebook that fits the region your adventure map is in and alter the entries as needed.
You can also create entirely new histories and your own table if you want too, though this obviously requires a bit more work. You can use the existing Histories tables in the BREAK!! rulebook as a guideline.
Regardless of which method you use, the Options Menu entry on Histories will be helpful here.
Once you have these things done, you’ve got enough of a setting to run a BREAK!! Saga with. There is no doubt you’ll probably want to build it out from here, but you can do that as you need or want to.
Let’s look at some quick outlines to get an idea of how this method might look. Please note that while they aren't complete settings (at the moment) they should give you a good idea of what you should be thinking about:
Concept: Thanatos Arch is a setting focused around a catacombs like city ruled by otherworldly and undead creatures in a world shrouded in perpetual dusk. The player characters are desperate souls delving into dangerous ruins in hopes of finding purpose in such a place, with themes of struggle, self-discovery, and glimmers of hope. It is inspired by the web comic 9 Gates.
For mechanical differences, it uses the Old School Dungeon Attrition rules from this Option Menu post. It's rough out there.
Map: The adventure map for Thanatos Arch has its titular metropolis in the center, with some adventure sites marked off around, under, and even within the city itself. At each extreme end of the map, the new (and likely very dangerous place) this direction leads to is noted. The GM really only needs to flesh out those new regions if the player’s show interest in them.
Character Options: The Battle and Murder Princesses of Thanatos Arch are modified flavor wise - rather than their weapons being born of their own emotions, they are manifestations of the souls of warriors past who’ve chosen the character as a host and new bearer. These ghostly warriors speak with both as well, in the form of the Battle Princess’s Soul Companion, or in the Murder Princesses case, via telepathy from the summoned weapon itself.
The available species for Thanatos Arch are Tenebrate, Promethean, Gruun, Rai-Neko, and Dimensional Stray. With the exception of the last one, these are re-flavored to be different sorts of devils native the realm.
Histories Table: Thanatos Arch uses a modified version of the Wistful Dark’s history table. The general histories are kept, but certain fiction aspects are changed to match the setting. For example “Shard State Patrician” becomes “Gilded Crypt Noble”
Concept: Maniac Metro is essentially an alternate “Other World” for BREAK!! - rather than a world closely resembling our own, it is a bombastic contemporary fantasy setting where the mundane things we take for granted are readily mixed with the arcane and supernatural. The players are workers in absurd gig-economy dealing with literal corporate overlords. It is inspired by the comic One Time Taxes.
Death is very rare in Maniac Metro, instead characters who would perish are instead injured in a thematically comedic way and are out of commission for the current goings on.
Map: Maniac Metro’s map is a bit more zoomed in than normal, focusing instead on the various neighborhoods in one enormous, sprawling city on an artificial island. Locations of interest are marked in each place as adventure sites and mini-settlements, and who runs that part of town is noted for reference. The only way to properly leave the city is also shown - a dangerous underground tunnel leading back to a vaguely named “mainland”.
Character Options: BREAK!!’s Callings aren’t changed a whole lot mechanically for Maniac Metro, but their flavor should definitely be worked around a character’s background concept. Raiders and Champions could be exceptional athletes, street brawlers, or super hero types. A Sage might be an ascendant office worker with a magical laptop instead of a grimoire, a factotum could be the greatest barista who ever lived, and so forth.
You might want to think about cars, or car like vehicles for a game in Maniac Metro. We're sure to publish something along those lines at some point, but for now you can probably re-work skimmers, walkers, etc.
Every playable species in the BREAK!! Rulebook is available in Maniac Metro, but as far as the city is concerned everyone is “human”. It’s rude to ask.
Histories Table: Maniac Metro uses the Other World history table, but with the following exceptions:
Oldtech Junker from the Twilight Meridian Histories added as an Outcast
Startech Adept from the Blazing Garden Histories added on as an Elite.