First thing I would like to ask is that you try to dumb down code to my level. You quickly tend to customize classes and use inheritance where it can be avoided. Even if it might be a better way of programming, it is also more difficult for me to read and understand.
I started the project to have something I can understand and advance, so for as long as it is possible I would like to avoid having a School/Brothel/Bank inherit from one Building class and having to modify class behavior like __getattr__, __repr__, ect.. Even for items you've employed "collections.Counter" inheritance (that I've heard of but never used before), I've seen a good 15 items system so far and non of them had to use any module while working great.
I know this is a nuisance but I would like to avoid having to go through documentation or hurting my head figuring out classes every time I wish to modify the game.
Alright, so I thought about what code I could write for PyTFall. There are lots of possibilities and most of them involve me designing how parts of the game will work. I'm not sure that's a good thing, as somebody else might want to do it differently. Therefore, we either should have a discussion previously or somebody with the authority to do that should decide how that particular feature should be implemented. Let me give you an example: Brothels
Brothels are as good of an example as any

Should they provide jobs and stat bonuses to inhabitants like in SlaveMaker?
Should their properties be decided by the rooms they encompass like in Otherworld? Should they even have rooms?
Yes, they should obviously have rooms but WM/Simbrothel type of rooms. After Alkion is ready (new version was released today and it is getting good, much of the coding is ready, now it is mostly about content and re-balancing) I will prolly translate it to English if time allows and we will have a game with a lot of different rooms

No need for two games...
They also already provide jobs and should provide bonuses during jobs if upgraded in the future. Also I had half a mind to allow more advanced upgrades like in SimBro 1x or Alkion through buying furniture and similar stuff, but that was planned for the advanced version.
Should they influence available customers, like in sibr1x (I think...)?
Can the player own more than one? Run more than one?
Yes, they already determine costumer's caste based on brothel's reputation. More than that? Like fetishes, I didn't plan anything like that but SW raised that issue. He wanted Brothels to attract costumer with certain preferences based on advertising but that wasn't in my original plans. Design was supposed to be simpler than that.
For now, I suggest keeping it simple, release a playable Alpha, then look at the game as a whole and decide what parts are more important and focus on those!
For the second question, please take a look at the game, Player is obviously allowed to own and run more than one brothel.
Not everything can be set in stone at this point, but some decisions will be necessary.
True, take a look at what's already there. On top of this brothels are supposed to have at least strippers after the lounge is bought, if you've read previous posts, you prolly already know that the idea was to have player balance Brothel's reputation (that influences costumer castes) vs ranks of girls working in the brothel. Strippers would rouse up clients that will later buy sex and entertain overflow of costumers getting cash out of them.
How many slaves can the player own? Many slaves means lots of work for the player, so managing each one of them should be simple (think WM here). Few slaves means lots of playertime for every one of them, so managing them can be quite involved (as it is in SlaveMaker).
Also was addressed somewhere. I tested the engine on 4 years old laptop with a logical equivalent of :
For 2 000 000 interactions (around 400 000 girls in game), game crashes on next day.
For 200 000 interactions (around 40 000 girls in game), next day calculations take around 7 - 9 seconds. Saving takes 20 - 25 seconds.
For 20 000 interactions (around 4 000 girls in game), next day calculations take around 1 - 2 seconds. Saving takes 1 - 2 seconds as well.
For 2 000 interactions (a more realistic scenario of 400 girls in game), next day calculations and saving are instantaneous. So we're in the clear to have a lot of slaves like in WM. Also, game will be be based around AP (Action Points) and I am planning to make managing/training any one - two unique slave/s VERY entertaining as well as running brothel but that is also planned for a more advanced version.
Many slaves means multiple houses can be useful. Few slaves mean a single house at any given time will be sufficient.
Many houses, many girls, less than half of them slaves if you've read previous posts. Girl's have kind of castes themselves that go from slave to royal and all will have different rights. Implementation will be half/half between the simpler SimBrolike and advanced WMlike versions of the game, how deeply implemented in the simpler version, only the flowing gamedesign will tell.
We could add a simple design document into the Dropbox, so each of us can edit it. A .doc file (not .docx!) would be a good choice, as most people will be able to edit it and pictures can be included if artists want to sketch GUI layouts or similar stuff. In this document, we could collect ideas and develop a common vision for this game.
Please lets not do that... it takes insane amount of time and pouring out brainstorms into such documents quickly corrupts the concept. Both of those I've seen happen in Alkion and a couple different projects. There many problems in projects with more than one programmer, in Alkion, it was mainly difference in skill between Eliont who studied to be one and can code in an impressive amount of languages, has specialization (media streaming) and learned Python just so he could code in RenPy in his spare time and me who just listened to lectures and read a limited amount of Python Documentation so I could try and code some form of WM2. I don't want this to turn into another Alkion

My advice is this:
Choose what you want to code, like brothels, ask here what that is supposed to be like in general and then simply write what and how your planning to code in .doc. You don't have to be to specific, just the general plan and how you're planning to implement that.
To get started, we could talk about a very interesting question: At this point, what would be the most fun, interesting or sexy new feature/improvement to the game (in your opinion)?
Jokers? Mission system? Traits?
I know a good one: Exploration engine

My idea was to finish the girlsmeets, finish the advanced logic for Brothels/Costumers/Girls/Traits. Finish every tool modders may require and release the freaking stable Alpha version, still without Jokers and some other stuff but playable, stable and with some fun content! Then work on adding jokers and other features that are secondary to gameplay to enrich the game, balance it out properly while during that time new and new content is created and then, release a beta, debug - release The Final 1.0 version of SimBrothel PyTFall and then after a short break, start pushing that into a more advanced game with territory control, advanced slave training, advanced Arena maybe even some form of exploration engine.
Long story short, I think the most amazing/sexy thing right now would be to release a working version
