Here’s a suggested change mostly about gunplay and ammunition.
So first of all, I think bullet penetration should be implemented. Walls, wood, glass, fences, etc should be able to be shot through, and both players and enemies should be able to utilize this. Simplified, going through one layer of material (a wall) can reduce the bullet velocity/damage by half, two walls by another half (or 75% overall damage reduction), and should not penetrate at all through two walls. If you wanted to do it realistically, it would depend on the weapon and/or the caliber of the ammunition. So perhaps an n19 can’t penetrate a wall, but a hunting rifle can, and a p90 can shoot through 2. All weapons should be able to shoot through glass with little or no penalty.
The way enemies should engage with this is that if you run into a building during combat, you should still be in danger of getting shot (but with reduced damage). They still can’t see you so will de-aggro after the same amount of time, but if they can hear you then they shoot in your general direction. Best chance of survival is either to quietly leave through a different exit or hit the deck, go prone on the ground and hunker down until they lose interest. Or shoot them back if you think you can kill them before they can kill you (assuming your weapon can maintain enough damage through a wall to still be effective).
There should still be plenty of impenetrable surfaces. Rocks, stone/brick structures, reinforced metal doors, etc. For gameplay reasons it’s important that trees remain impenetrable, but all other surfaces (within reason) should have penetration.
This next part is more of a wishlist, but it has to do with guns so I’m adding it here. Ammunitions and weapons need to have their weights reassessed. They don’t need to be strictly speaking realistic, but when individual rounds are physically smaller they should weigh less, and same goes with guns. This is not a huge gameplay priority though, more of a finer polish.
I would personally also love it if individual empty magazines became a loot item, and that it was necessary to load individual magazines at the PLUNDRA or the consumables crafting station before going out on expeditions.
This shouldn’t impact the weight too much, but they should have a small amount of weight to them. Instead this would be meant to be a way to make players think more strategically about how much ammunition they bring, and to have another strategic decision to make in terms of reloading a magazine mid-combat. Early and mid-game you probably won’t have enough magazines for your auto and semi-auto guns to constantly spray and pray at enemies because you’ll empty them mid-fight. So in that way it’s also a subtle mechanic that encourages players to slow down and make meaningful decions about combat, stealth, and general survival.
In my opinion, any gameplay scenario that forces you to retreat (even momentarily) is a good gameplay scenario and is a big part of what makes this game stand out from others like it. This wouldn’t prevent people from becoming somewhat overpowered mid-to-late game, but that’s not the point. You’ll eventually be able to have enough individual magazines made for all of your individual guns that you trivialize this mechanic, and that’s the reward you get for slowly conquering the scarcity aspect of the open world over the course of your playthrough.
I have a short closing remark. I genuinely believe that the suggestions I propose would improve the gameplay overall and reinforce what already makes the game great. I’m not the kind of person that thinks it needs to be more hardcore/realistic and I’m also not the kind of person that wants to make it super casual and COD-like. I think that Generation Zero has this wonderful balance of being pretty hardcore already while still having very little tedium, being easy to jump into, and even allows you to feel very powerful from time to time. I see a lot of feedback from people who want to radically change the game in either of those two directions. I think Generation Zero has merits of its own as it currently stands, and that drilling down into what exists already is a much better way of going about improving it.
Thanks for reading my post!