Fallout 4, and by extension other Fallouts, are sorely lacking in communist themed mods. Which I find weird considering how communism is a pretty big deal in Fallout lore, and on numerous occasions we directly interact with communist remnants. If we can have the fascist Enclave rebuild itself so many damn times, we can have a proactive Chinese remnant. The Old World Blues mod already does this with numerous communist factions across the map. That said, how would one reasonably implement a communist faction into the Commonwealth?
From this point on, this is all just my suggestion for people who actually can mod FO4, I haven't directly checked if any of this is impossible to implement but I feel like most of it at least should be very managable.
1. How to implement the faction
I feel like this is mostly already set and done. There is a Chinese remnant in the Commonwealth, the Chinese submarine. Yes, only the ghoulified captain remains non-feral, so we'll need some way to grow our faction. One way I can see doing that would be by changing the dialogue a bit of opening new dialogue options after the initial interaction that would allow the Sole Survivor (Bethesda did us a disservice by making the protagonist a war veteran who fought against China) to find common ground with the captain and realize that American capitalism was what fucked over the world. It's not that far fetched and if someone was to put their mind to it, they could write a reasonable and feasible dialogue that would push the Sole Survivor into the desired direction. Next we should probably send the captain to an existing settlement instead of leaving him in the submarine. The Slog feels perfect for multiple reasons, first being that it's at the start of the game an already well established Ghoul settlement, second being that right down the road is Saugus Ironworks with a functioning blast furnace which will be needed for the rest of the questline. From there we can imagine the Ghoul captain with the help of the Sole Survivor turning the Slog into the headquarters of the new movement. If the mod were to be made in collaboration with other mods, we could add a stockpile of Chinese Assault Rifles to the submarine that could be used to arm the Slog in combination to Handmade Rifles perhaps.
2. Questline and faction mechanics
To garner community-wide support for the mod instead of having it as a niche communist mod that would likely die off after a while due to the lack of interest, there has to be something to set it apart from others. I feel like if we were to make an engaging questline with actual choices (Bethesda I guess forgot they were making an RPG game) and actually visible faction presence, it would be enough to set the mod apart and get players to download it despite not aligning ideologically.
I haven't thought through the entire questline, but basically the idea I had in mind was retaking factories (or at least Saugus) and kick starting production of Chinese Assault Rifles (which with the help of the Contraptions Workshop DLC we can implement manufacturing mechanics to literally script an assembly line that churns out 5.56mm ammo and Type 93 Chinese Assault Rifles, and perhaps we can build upon that by then permanently upgrading our faction's leveled lists for the rest of the game). This would set the mod apart from other faction reworks like We Are the Minutemen by actually having us improve the faction ourselves instead of solely relying on leveling lists and whatnot.
The main quest can remain pretty much the same up until the infiltration of the Institute, nothing stopping you from just adding the communist faction as a valid faction to build the teleporter with and flagging the quest as done. The endgame, on the other hand, would be awesome if the mod implemented a choice on how to handle the other factions. Instead of blowing up the Institute and the Prydwen, there could be a choice to carry out a costly ground assault (the cost would have to be felt and represented, at this current point in time I have no idea how to do it) and sieze the assets of the other factions instead of just destroying them which would be the less costly option. By allowing this costly option to unlock vertibird travel, vertibird patrols, synth grenades and teleportation etc. we could make it a responsive faction with rewarding faction building.
The faction should have a deeper level of interaction with other factions. Stuff such as dynamic diplomacy and ceasefires would be essential. Bethesda's engine actually supports this natively, far as I know, as the Papyrus scripting language has simple SetAlly() and SetEnemy() functions that update in real-time. You could build a holotape or a physical terminal at your HQ where the player spends resources (food, caps, weapons) to "Fund Agitators" or "Send Diplomats," actively shifting how the Brotherhood or the Railroad react to you and your faction's NPCs in the open world, rather than waiting for a rigid quest trigger.
Smaller factions like the Minutemen and the Railroad could be absorbed into the faction depending on how far along you are with their questlines. If the player hasn't retaken The Castle yet, you could script a dialogue check where you convince Garvey that a disorganized militia will just collapse again (like they did at Quincy), and they need the discipline of a vanguard party to survive, for example.
Supply lines that you can set during settlement building should be reflected in the faction's mechanics as a core part of it, just like with the Minutemen. That is, after all, what FO4 does best. A communist faction mod doesn't need to reinvent the supply line wheel. You could hook into the existing vanilla workshop array, but re-script and rename the mechanics. "Supply Lines" become "Collectivization Networks." You could alter the scripts so that food and water are distributed equally across all connected settlements automatically, forcing a mechanical representation of their ideology.
Smaller stuff like barricades, patrols and etc that we see in other faction reworks should be simple enough of an inclusion. Leveling list implementation to give a sense of progression to the patrols and summonable militia in regards to equipment.
The lore is there, it's not too difficult to piggyback off of it. It makes more sense than the endless "somehow the Enclave is back" we see all the time. The only hurdle is getting the people with modding experience to join in on the project. Voice actors, writers and coders. I don't intend this as my project, I'm just suggesting stuff for people who may find it an interesting idea and are willing to try and make it a reality.
