There are some extremely simple things that could address a lot of the issues people have, some others require a bit more work.
The issue of “too many guns” is totally solvable by moving json entities to new files, it’s just a matter of looking through the files and doing copy/paste on them, and interacting with git to make the PR.
Basically, find unrealistic or unrealistically rare guns and ammunition, and move them to a mod file with a description of what kind of content it is. some examples:
A “rare guns” mod, that takes a lot of the “one in a million” guns that are in the game, but in reality only exist as a handful of prototypes. One of my favorite guns in the game is the American-180, but in reality they are so rare that you would NEVER see one unless perhaps you devoted yourself to tracking one down, and even then it’d be hard. There are other guns much rarer than that, but in the game are fairl common, on the order of 1/1,000 chance of seeing one, rather than the more realistic 1/1,000,000,000.
A “scifi weapons” mod, that simply takes weapons and items that don’t currently exist and moves them to a mod, possibly several for “near scifi” vs “far scifi”. A laser rifle might go in “near scifi” while a plasma gun would probably belong in “far scifi”. Power armor would likely go in some scifi category as well, or just move into its own mod.
“unrealistic” items (better name needed) might have their place in a mod, such as the various flaming weapons, and various cobbled-together items you can’t expect to work in reality.
Just because something is in the mods folder doesn’t mean that if you download DDA and play with default settings it won’t appear. There will be quite a lot of stuff I’m sure that gets moved to a mod, but is configured to be part of the default game. Similarly this initial sorting of things to mods or core isn’t final, the structure we create will likely continue to be useful indefinitely, but the end goal is to have things tagged such that they can be included or excluded based on various categories, which will make it easier for us to add things to categories, and easier for players to pick what they want in their game.
This leaves the question of what belongs in the “core” game. This is a really tough question. For monsters it’s fairly simple, we’ll look at moving fungaloids, worms, and triffids into their own mods. Zombie-free cataclysm really doesn’t work, and if you want that game you can simply set zombie spawn rate to 0 anyway, so that leaves zombies and animals in the core game. Robots will probably be shunted to a scifi mod, with the exception of turrets, which are deployed in some capacity in several places in the world today. For guns it will include a selection of the most common guns in various categories. With probably several different “more guns” mods to chose from. Some mods might follow a theme, like the rivtech guns moving to their own mod, etc. For utility items, I don’t see most non-scifi tools and other items moving to mods, there doesn’t seem to be much demand for it. For clothing, various specialty items might move out to mods, but I don’t see a huge need for paring down that list either. Feel free to propose items to be pushed out of the core, but if it’s an item that exists in reality and is reasonably common, expect an uphill battle. If it’s an invented item, or is in reality incredibly rare it should move out to a mod.
The code that runs the game would maintain support for everything in the mods, but if it’s not loaded, it won’t appear in the game.