I see on the roadmap some ideas about putting the Slums inside the city walls. Information is scattered, but according to the original game texts, the Slums are located outside the city walls. You encounter Isabella while "passing through the slums at the Border of the Fogs." In older versions of the game, the button for leaving the Slums was labeled "Walk to city" instead of "Leave the Quarter" (in the 2.2 dev version).
When you patrol at the Border of the Fog and encounter various monsters, notice that you never actually enter the Fog. Is it even possible to be "in the Fog", or is that just how citizens of Eternal Rome refer to other worlds (in the Fog / beyond the Fog from the perspective of Rome is "anywhere that isn't here")? If the edge of the Fog acts as a dimensional portal, then passing through the border of the Fog either teleports you to an "in-between" realm (in which case "in the Fog" is a specific place in the multiverse) or it teleports you directly to another world (randomly or with control if you have the requisite knowledge and skill - including but not limited to magical ability). If the edge of the Fog is not itself a portal but rather the Fog contains portals somewhere inside it, then it would be possible to physically enter the Fog without being teleported right away, but you would be at risk of stumbling into an unseen portal at any time (because obscured in the Fog). In the latter case, it might be possible for even non-mages to navigate the Fog (as long as the locations of the portals don't change). We know it is possible to pass through the Fog and control where you end up, because various characters mention business arrangements with specific worlds, implying there are ways to travel back and forth.
We know the Fog can be entered deliberately from other worlds by those with magical ability (for example, this is how the Nerd arrived in Eternal Rome, according to his backstory). We also know the Fog can be entered accidentally (for example, this is how Balalaika, leader of the smugglers, along with her former military unit, came to Eternal Rome unintentionally).
We know that the city of Eternal Rome is surrounded on all sides by the Fog. And we know that the distance from the city to the edge of the Fog changes frequently (perhaps constantly).
Reverend Molaru, Archbishop of Taurus House says: "A priest`s duty is to drive away the Fog from the Houses. Every day, on the altars of the cathedrals, sparks of creation are burned in ritual acts and Fog backs off. The Archbishop is in command of the priests and is personally responsible for the well-being of the territories around the Fog." I suspect the word "around" there is an incorrect translation and should read "surrounded by." The description of Archbishop Nirelis is: "This mummy is so old that he unravels as he moves, but Nirelis has great magical power and influence. His work is managing the temple, which removes Fog from the boundaries of the House." There are two other Archbishops, Reverend Porter and SHAITANA.
So each of the four Great Houses (Camira, Corvus, Serpis, Taurus) has priests responsible for spending sparks in a ritual that pushes back the Fog from their quarter of Eternal Rome. All territory within the city is under the jurisdiction either of the Vatican (White Town) or one of the Great Houses (they each have a "Quarter" of the city). As White Town is in the center of Eternal Rome, the four Quarters wrap around it.
We know that Eternal Rome has at least one external city wall all the way around it, because there is a city gate. It is not stated whether there are multiple gates. The gate in the game is labeled as singular ("the" gate) without stating which Quarter it resides in. So it might be that Quarter has its own gate, and going to "the gate" means going to whichever one happens to be nearest. It would make sense for each Great House to have its own gate, so that they do not have another Great House limiting (or monitoring) all of their comings and goings. Of course, having a gate is also a risk and requires maintenance: it is an easier point of entry than the wall for monsters seeking to enter the city, and it also needs guards to prevent the desperate riff-raff in the Slums from entering the city without permission.
When meeting Isabella, the slaver says: "the guards will not allow you into Rome proper without the sign of any of the Great Houses. I’m sorry, but I can hardly help with this. You need a recommendation from the recruiters." And Isabella says: "There are different ways to get into the city. I do not have sparks to bribe the guards, but I can pass as a slave of a respected member of the guild." From this, we know that there are guards, passports (effectively, if not literally - entry passes might take the form of tokens or the guards might have a list of authorized persons - but regardless entry is regulated by the Great Houses), and recruiters (from the guilds or other citizens looking to recruit from the Slums). If we think that each Quarter has its own gate, then to pass through a particular gate you would need approval from the Great House that manages that Quarter, and while they might accept the sign of another Great House, depending on relations between the Great Houses or their level of suspicion, they might not. While not overt in the game texts, in a city with rival powers, there must be conflict at times.
At the base camp that players can visit at the Border of the Fog, the sergeant is described as "in charge of one of the many fortified camps on the border of the Fog. He and his soldiers are the first line of defense against all dangers that enter Rome from other worlds." And he says: "Civilians do not belong here, you had better go back to the protected area."
So we know that there are multiple camps surrounding the city. Where are the Slums in relation to these camps? Is there a second wall between the Slums and the soldiers' camps? This does not seem to be clearly stated, but we can make some inferences.
The player home in the slums has the following description: 'You had to live in the remains of a house that was half-eaten by the Fog. For slum this place was built very thoroughly, but staying here is not comfortable at all, and most importantly - very, very dangerous.'
I interpret "half-eaten by the Fog" to mean that anything the Fog touches, vanishes. If the rituals are not maintained by one of the Quarters, the Fog creeps closer to the city walls, and could even creep past the walls into the Quarter itself. If the Fog ever got close enough to the city to touch the walls, they would vanish too. There must be a limit to the effectiveness of the rituals (the Fog can be pushed only so far back and/or only so often) and there must be variation in how close the Fog approaches the city on a given day. It is unlikely that the city walls would be placed somewhere where their vanishing is even an occasional problem. Maybe some Great Houses are more effective with their Fog-pushing rituals and so their portion of the city wall is farther out. It is doubtful that the wall is perfectly circular all the way around the city, given how much of a premium is placed on space.
If any land outside the city walls is deemed "safe" there would be immense pressure from citizens to bring that land inside the walls. In other words, the land outside the main city walls is land that citizens do not want, which means it is land that is not considered safe. So the edge of the Fog must sometimes approach quite close to the city walls, vanishing anything in its path (such as the portion of the slums built outside the walls in that area). The residents of the slums in that area would need to flee closer to the city wall or to an area where the Fog is not as close, then return later when the Fog retreats again to rebuild (except for the unlucky ones who get caught unawares, possibly including the previous resident of that shack in the slums).
Also, because the citizens do not want their wall to be eaten, they would leave some buffer space beyond the wall where the Fog very rarely comes (rare but not never, so not safe extending the wall further), and so the land closest to the wall would be the most valuable (being least likely to get eaten). From the citizens' perspective, the residents of the slums are the least valuable persons in Eternal Rome (that aren't worth the effort to make dead), so it seems unlikely that they would invest in building a second wall (that would need to be regularly rebuilt, necessitating import of raw materials) to protect the slums from monsters. The residents of the slums are themselves a buffer to delay the ravening hordes of monsters constantly emerging from the Fog until patrolling soldiers from the camps can hunt them down. Why bother protecting the slums at all (with the soldiers)? Probably the soldiers are really more for protecting the city itself (some monsters can fly, and if enough monsters are allowed to accumulate, they could breach the walls or overwhelm the gate guards). Also, some of the residents of the slums are employed within the city, and having a place for their wage slaves to live outside the walls means the citizens can hoard more of the land within the walls for themselves, so the citizens have an interest in maintaining a minimum level of safety outside the walls so they don't have to constantly replace their workers.
So, how much space is there from the walls to the border of the Fog?
Considering that what the player encounters at the Border of the Fog is representative of what is constantly happening there, not only when the player decides to patrol, we see that there are hapless women from other worlds frequently stumbling out of the Fog, and then being caught and raped by monsters that emerge from it soon after. So the distance from the border of Fog to the Slums must be far enough (most of the time) that these women can't immediately run and hide between buildings, or else we would be encountering these scenes whenever we visit the Slums instead of only when patrolling along the border.
There is also mention of enemies "fleeing the battlefield" when you prevail in an encounter, which suggests at least some amount of open space along the border. Considering that the priests perform their Fog warding rituals daily, my interpretation is that Fog advances a large amount every day, and the rituals push it back a more-or-less equal amount (with some give-and-take day-to-day, but an equilibrium is maintained over time). The space over which the Fog moves each day would be left barren or filled with random structures taken from across the multiverse (like waves depositing shells on the seashore). It is within that "high tide"/"low tide" space that the soldiers from the base camps patrol, and the most dangerous time to be in the Slums would be just before the priests do their daily rituals, when the Fog has reached its closest approach point for the day.
So when the Slums are referred to as being "at the Border of the Fogs" when you meet Isabella, it does not necessarily mean that the edge of the Fog is right next to the outer edge of the Slums, but at "High Fog" (to coin a phrase) it comes quite close. And anything left beyond the outer edge of the Slums usually vanishes the next day when the Fog rolls in.
With this interpretation, the base camps would be built close to the city walls and would have Slums on either side of them. In other words, the Slums are sandwiched between the city walls and the Fog, with soldiers patrolling the empty space between the Slums and the Fog, following the shifting boundary edge. Residents closest to the camps would be safest, of course.
Residents of the Slums are at constant risk of attack by monsters that slip past the patrolling soldiers, particularly at "High Fog" when there is little space between the edge of the Slums and Fog for the patrols to move around in, and there is even risk of Slums residents having their homes (and themselves) vanish into the Fog when the priests have a bad ritual day or the Fog is more rapacious than usual.
It is worth (pun intended) noting that the key ingredient for the Fog warding rituals, Sparks of the Flame of Creation, are contained in all living souls (according to game texts), and they can be extracted and imbued into objects, which forms the basis of enchantments as well as the physical currency of Eternal Rome. Sparks can be dissolved into a soul and then used to power magic, as described when the master casts spells or your slave takes enchanting lessons. Presumably casting spells without first absorbing Sparks is possible too, but would deplete the soul of the caster.
That gives an idea for a lore-friendly gameplay change: allow casting spells when you can't afford them, and drain the master's health [strength, allure and libido] stats instead. It would apply only when the slaver has run out of physical sparks. It would be interesting to see if this could be exploited by players. They could deliberately wait to take a loan until the end of the decade and meanwhile spend their master's stats on magic to help with training. But once the loan is taken, they would be spending physical sparks again for magic until it runs out, and on the hook to pay back the loan plus interest, discouraging any unnecessary spending. Other sources of income - selling previously and cryo-stored trained slaves, winning in the arena, etc. - could be used to avoid game over for a longer period, while keeping saved sparks deliberately as low as possible. Overall, I doubt it would significantly alter game balance, but it might be enough to save an otherwise hopeless situation. But we could make an option for the player to drain themselves instead of using physical sparks even when they have enough, introducing another dimension of gameplay strategy by turning the master's stats into another resource to be exploited. The drain rate would need to be balanced to exceed the rate at which the master can train up those stats, of course. For the first few slaves on a hard start, spending some of the master's stats instead of sparks could give more time to achieve difficult guild contract specializations like concubine, gladiatrix or pony, or shorten the time to complete the contract if the sparks saved on magic were spent on classes at the academy, but depleting the master's strength can lead to death, so it can only be taken so far...
There is also mention of the Vatican providing Sparks daily to each of the Great Houses, with the Praetor in each House being the person responsible for these deliveries. Where does the Vatican obtain all of those Sparks? We know that sparks exist in living souls, but can they be extracted by force? Does the Vatican engage in daily vampiric (soul-draining) rituals? One reason to doubt this is the practice of selling slaves to the butcher. If a slave is worth 5 sparks dead, then the Vatican must not be able to get more than 5 sparks from them while they are still alive, or else unwanted slaves would be sold to the Vatican instead of to the butcher. Still, even if the Vatican could forcefully extract only 1 spark per soul, if they have a method of obtaining victims that costs less than that, they would turn a profit.
Most of the women who wander in from the Fog get enslaved, and all slaves are female. What happens to men who wander in from the Fog and don't stay in the Slums? Many of the story mode master characters have stories about coming from other worlds. They all somehow avoided being murdered in the Slums and somehow became slavers. Butler's story mentions that he "put a lot of effort to gain the status of a slaver." Of course there are other Guilds besides the slavers (for example, the Illusionist Guild that maintains the illusion of the sky and sun for the artificial beach, which is actually in a cavern in the Serpentine Quarter). So some of the skilled male migrants arriving from the Fog may be able to secure jobs for themselves and survive that way. But if they can't show their worth, what is done with them? They could be slaughtered for food, but I don't see any text suggesting that in the game (pigs are specifically referenced as female). Hmm...
In addition to "honest" workers (residents of the Slums who have day passes to go to work in the city), we know that the Slums contain gangs of thugs (we sometimes see them catching girls at the border). Probably the members of gangs who are not also in the first category (workers) eke out their meager living by 'protecting' (extorting) residents (pay the dominant local gang to leave you alone; they try to keep other gangs away so residents keep paying them) and by capturing men and women who stumble out of the Fog and selling them to Slaver's Guild representatives or delivering them to recruiters in the hope they might have some valuable skill. This possibility of value to a recruiter is probably how most men emerging from the Fog survive their initial encounters with the gangs; they get captured and handed to the recruiters for a few sparks, or rejected and then either get forcibly inducted into the gang that caught them -- attrition undoubtedly being high -- or sent back into the Fog (dead or alive at the whim of the gang in question).
Naturally, as available space is finite, the Slums are very densely populated and the residents of the Slums must be fiercely competitive as every resource is scarce. Anyone living in the Slums must have protection of a gang or a Great House or Guild in the city (as the player does, being a slaver) to discourage other residents of the Slums from stealing everything they have, killing or enslaving them.
If the equilibrium between the priests and the Fog boundary ever shifted outward (meaning that a section of the Slums is no longer at constant risk from the Fog), the Quarter of the city on that side would expand outward, taking over part of the Slums there, because the citizens in that Quarter would hardly care to leave the expanded territory to the poor. But equilibrium shifts outward probably do not happen (the rituals are well-established, as is the behavior of the Fog: the rituals are probably about as effective as possible already). On the other hand, equilibrium shifts inward could happen when a Great House falls out of favor with the Vatican. Their Archbishop would be given less Sparks for rituals and would lose some ground (and some of the Slums) on that side (but probably the Vatican still would give them enough sparks to avoid the Fog reaching the city wall), until they patch up their differences. That would be tough luck for the Slums residents from that area, who would have to relocate around the outside of the city to the Slums in the territory of one of the other Great Houses.
Incidentally, there is mention of "Camira war camps" in the Fenris master character's background, but I see nothing else in the game text about them. Possibly this is a reference to the base camps outside the section of the city walls belonging to the Camira (Outcasts) Quarter. Or possibly there are some wars being fought elsewhere in the multiverse that the Outcasts are involved in. (If the Fog can be navigated, it stands to reason that Eternal Rome can wage war against peoples in other worlds and establish colonies, demand tribute, and do the other types of things that foreign invaders do after defeating the locals.)
