Cataclysm: Dark Days Ahead has an amazing systemic world, interconnecting the world to make it seem real, somewhat. I have noticed that many non-player characters you can happen across seem to stand in place eternally, acting as quest-dispensers. Shopkeepers, too, stand within their impenetrable boxes, and when killed, locks you out of all possible quests, never replaced, in the case of the merchants in the Refugee Center, and time for NPCs seems to stand still. In terms of dialogue, that can be fixed quite easily, I shall instead focus upon more, “complex” elements.
In terms of what non-player characters can do, I suggest expanding this further for static non-player characters. The refugees living in the Refugee Center could wander about, chat with one another, travel to the food stocks in one room, then to the dining area to feast. There could be a chef, even, spawn within the dining room and cook meals. When they begin to tire, they may travel to their own personal cot to rest upon, until they wake, merchants and guards included. If we wish to extend this further, they may garner a need to relive themselves (in one of the restrooms). The merchants could posses a key to their booths, locking the entrance each time they exit, to deter the would-be thief. From time to time, wandering scavengers may voyage to the center to exchange their wares with the shopkeepers, providing a diversified stock each time the player trades with them. The arsonist located within the center could travel to nearby towns and demolish buildings, preferably those which have been looted prior, disassemble furniture, etc. The player could find those ruins within a certain radius around the Refugee Center. Lone or small bands of survivors may begin to reside around the center, with noticeable activity, too.
The refugees could posses varied, unique backstories, and may hold jobs around the center, working for pay, through maintenance, scavenging, or guard duty. They may randomly generate missions for the player to undertake, dependent upon their needs, something similar to the “Smokes, lets go” mission.
Missions, too, could be improved. If you opt to undertake a job for someone, and wait a lengthy amount of time, someone else may have already completed the mission for them, rending your rewards. The mission-giver’s statuses may shift negatively, if infinitesimally slight, towards the player, reflecting their dislike for your lethargy. Obtaining further missions from them may become more complicated, and if you have angered them enough, outright impossible, which could impact your affairs with their associates, though to a lesser extent. Some missions may only be obtainable after a certain number of days have passed, a “days_after_cataclysm” tag, pre-constructed or randomly generated.
To further allot for improved world fluidity, bands of survivors could form and expand, constructing bases throughout the world. The player could trade with them, and may aid in forging inter-faction alliances, finalizing trade deals between these varying groups, or utilizing political intrigue to seize power or spark feuds and wars. In addition, the players standing with one faction might affect your standing amongst another, say, you could forge bonds with the Hells Raiders, but the Free Merchants and the Old Guard may shun, or attempt to kill, you.
Of course, this presents opportunities to improve non-player character artificial intelligence further. Providing and example, the team which founds the Tacoma Commune could path to that location, avoiding danger along the way. Instead of loitering within the barn, the Overseer could shelter within the house, take stock of existing recourses, and other NPC’s may begin to construct shelter, and the player may discover them going about their business. Those who farm could plant and harvest crops, feed livestock and till soil, in addition to the behaviors mentioned earlier. The lumberjack may chop nearby trees, craftspeople could refine material, etc. In fact, caravans of exports may leave the commune, and be delivered to the refugee center, where they are exchanged for currency, perhaps utilizing the (relatively new) functioning backdoor. Later into the Cataclysm, new sites may spring up, allowing for similar trade deals to be procured.
Of course, the center itself could expand, too. In the event that the player provides their aid to the Tacoma Commune, the refugees may expand the center, allowing for them to take on more refugees, and may construct new stalls for merchants, transforming the center into an economic hub. The player and NPC’s may invest in these merchants, turning post-apocalyptic profit. These sort of trade deals could occur between the player’s faction camps and other groups.