This project is very experimental, its going to be Fallout on very unusual for it engine: Dungeon Master. I have with it some experience and known that is enough flexible to combine more or less both games.
Survival: DM have big advantage in this part. There is unlimited ways to complicate life. For example you must break table to get wood and use to make fire. Kill rat to get dirty raw meat, then wash it, grill on fire and even use cutlery to eat it (am already made rpg with such complexity but in medieval world)
Adventure: DM have drawback here, but dialogs and quests will be possible, just look simple as in FoT Awaken mod.
Zombies: Most of monsters will be something between mutant and zombie, they will be called "infected" and each hit from them can cause infection (which will work as DM poison)
Skills: Each character will be master in three skills (similar to Fallout tags) he cant learn too much beyond that and its drawback, but advantage is that there could be around hundread skills to chose. Instead of create character, here is creating team. Champions will have profession and skills connected to it (for example engineer, nurse, trader, outdoorsman etc)
Alternate to magic: It will be completly removed, instead of this will be hacking. Combinations of symbols is code which may open particular door or run terminal. (if you wonder how it work: each "spell" create different invisible dissappearing obiect on floor which toggle trigger)
Guns: I known how make them in DM so there may be lot of modern weapons and ammo, but beside this also primitive weapons.
Puzzles: Both engines are on the same level, it only depend on creator how much he use triggers. It will be not just zombie slayer but require think to make progress.
View and moving: To me old school rpgs with 90 degree rotate and step movement are still enjoable, its different playing experience from Fo1-3 and it could be advantage.
Walls: DM seem to have drawback as game designed only to underground labirynths but i found method to make high walls and outside landscapes, so its not drawback anymore (can look like Perihelion, Hired Guns etc)
Story: Game will begin in Vault12 under Necropolis where you take team and go outside (trough cave, severs and street) Town will be big and look like kind of labirynth of street ruins, barricades etc. Most part of game will take place in that town (explore just one building can take few hours) Ofcourse it may be enlarged later to other towns shelters and other places.
Resources: Impossible to grab everything from Fallouts, for example vault wallset i made myself. But few things as FoT portraits, menus, scenery, items, music etc will bring atmosphere to feel familiar.
Demo: It will take month to relase demo and around three months fo complete. Here is few early screens.
Other screens are here: