Bases are a topic I don’t see a lot of suggestions for, so here’s my two cents.
With UII having more of a focus on survival, instead of the large, ugly castles, or the grotesque mass of timber and steel that is freeform building, I propose more humble abodes. In most survival games that allow freestanding bases, the system to build them revolves around a sort of, panel system, now that I think of it it’s quite hard to describe, but you know what i’m talking about, the building systems in U3, Rust, Ark, and many others tend to follow a very similar template (with their own differences of course but generally they tend to resemble each other).
There is also the building system seen in The Forest, which operates off of fixed blueprints for structures, albeit with custom buildings that function similar to the system described above.
Both of these systems have their own merits and drawbacks. A “forest style” building system looks better but might to be more restrictive to players who want to build a cool base, whereas a panel style building system offers lots of flexibility but might result in massive bases that kinda ruin the whole “struggling to survive” vibe.
For UII, I propose a hybrid system, smaller sheds and cabins, as well as palisade walls could be built off a fixed blueprint, larger bases would use a panel based system, however, there would be a structural integrity metric, both so that skyscrapers aren’t as easy to build as they are in U3, and so that you can’t bridge right over somebody’s perimeter defenses (walls, minefields, etc.). Maybe there could also be a system that tracks how big a base is, so that larger turned hordes would attack it.
I also think that implementing better systems for traps could help with getting raided early on.
Addendum 1) Interiors
Just because the undead are hunting you day and night doesn’t mean ya can’t get cozy, bases in 3.0 (and a lot of other games) can feel pretty bland, rugs, chairs and lights might help with that. Perhaps even a “comfort meter”, not being comfortable wouldn’t have any negative effects, but a higher comfort stat would come with benefits such as food and water not depleting as fast. Maybe a radio to quell those old world blues and get info on coalition supply drops.
Thanks to y’all for reading, I undoubtedly missed a few things so I would love to hear criticisms and suggestions down below.