Most of my characters reach endgame off of a single city, maybe two cities if I don’t find enough books in the first one. My 10 survivor series is taking place in a city that is roughly 18x18. I’ve already found 2 labs, a sugar house, a hospital, a school, looted maybe 10% of said city, and I have…
Vehicle with solar, turrets, all the books for end game gear, more trees, planks, nails, scrap metal, and rocks than I will ever need… lots of shotguns… swamps where I can craft infinite ammo…
There’s a portal that spawns infinite enemies if I so choose. Sustainable farming is tricky on 90 day seasons, but I found a seed stash that will make it possible. That doesn’t include foraging every season change for a ridiculous number of dried veggies and eggs.
By the time I leave the city I will have at least one set of full heavy survivor armor, a decent solar vehicle, and everything I could ever want to craft. All that’s left would be scouting individual POI’s to find rare uncrafteable items.
In terms of flavor, a limited world size would be an interesting option. It would NOT, however, add much difficulty. A single city is already more than enough to reach end game off of.
In terms of managing NPC’s / factions / reality bubble, being able to simulate a 30x30 overmap grid would be sufficient to make things interesting regardless of world size (and would be a desirable feature to pursue regardless of world size).
Personally, I reach endgame off of the first city or two, then either die to a stupid mistake or get bored. Changing map limits, at least for me, wouldn’t change anything.