Could do some work to tweak where animals spawn, give them a range that’s a little wider than their current forest-only tendencies. Cities could actually wind up relative havens from wildlife, instead of the usual forests being safe from zombies thing I typically do.
Heck, you could write up some new buildings for cities - most cities could then be utterly decimated, filled with partially collapsed/decayed buildings, suggesting the military Launched All the Nukes and that’s why there’s so few people, alive or undead. That’d do a good job providing cover and partial shelter from weather without giving you a shitload of free houses to choose from. I always found being able to shut any old door on cougars and bears felt a bit cheese anyway. An intact home should be a prized find.
Maybe make infinite-food supplying mobs/structures like bees and their hives rarer, but make the range bees will wander from said hives far larger, so you’re encountering threats from them far earlier. I assume they would also be made somewhat meaner, as per previous dangerous animal mod suggestion.
Maybe bring back acid rain in some form for this mode.
Make minefields slightly more common, if you’re feeling like a particularly massive jerk to players. XD
I would be concerned about how labs would be affected by this. Would they only have nether creatures? Would the accessible lore related loot just be easier to get as a result? (wait, there IS lore related data on the cataclysm you can find, right?) I would want to avoid free-roam mode making it easy to find “endgame” fun places/items uncontested. Not that we have a true endgame, but you get my intentions.
Some things are already available in game by just selecting certain world options, but a nice pre-selected loadout with a few extras might be interesting for those who prefer the “innawoods bear grylls minus the pee” approach over that of “bullet-man versus the city of ten thousand zombie hordes”. I feel like it needs a little something further to really push it to that ‘unique game mode’ level, but it’s not a bad idea and I happen to like player-versus-environment conflicts.
