Inside Vault 88
Building and Resources
The Scrapper and Strongback perks will come in handy as will an established hoarding problem. You will be able to scrap a lot of debris around the vault area, but having some extra rubber and ceramic will be useful, too. Doctor Sun in Diamond City will have you covered with his shipments of rubber and Myrna at Diamond City Surplus has shipments of ceramic. Steel is the main structure component, but there is an abundance of it in Vault 88.
Workshops
There are four Workshops in Vault 88. Unlock them in Better Living Underground and Explore Vault 88 to have access to the entire buildable area of Vault 88. Similar to other settlements, you can assign a settler to create a supply line to share resources and inventory among settlements.
Entrances and Exits
There are three ways to access Vault 88. The first is the main 9 cog classic vault door. The other two are on opposite sides of the cave the vault has been built in. One is in the North-East Sector and puts you in University Point and the other is in the North Sector and puts you by Milton General Hospital.
Settlers
You will interview the first three settlers, but after that the settlers will just appear as they have in previous settlements. An early description of the DLC indicates that you will be able to change the appearance of settlers using the barber chair or surgery chair, but sadly they're just for your own use.
New Items
You can build Vault-Tec Workshop's new items outside of Vault 88 in other settlements. A gear logo indicates all new items. All new items, except the four Vault-Tec prototypes, are available to you immediately after unlocking the first workshop as a part of Better Living Underground.
Population Management Terminal
The introduction of the Population Management Terminal finally allows you to easily identify unemployed settlers and assign them jobs. You can also use it to locate your companions.
Using the terminal to find a companion triggers Overseer's Most Wanted. It's not a quest but instead places a waypoint indicator for you to locate your companion. You can toggle the indicators on and off through the terminal, which will remove their name from the Overseer's Most Wanted list on your Pip-Boy display.
Vault-Tec Prototypes
The prototypes from the experiment are found the Vault Resources category. They provide temporary boosts when you use them. The Power Cycle 1000 offers an endurance boost, the phoropter gives you a perception boost and the slot machine will give you a boost in luck.
Furniture
You can see a sampling of new furniture items above. Some new items like the pommel horse provide entertainment for the settlers and benefit you as well. Use the pommel horse for an agility boost and the weight bench for a strength boost.
Decorations
You can see a sampling of new decoration items above. All of these items are purely cosmetic for now. Some, like the posters, come in new and old states. Most are new vault specific items and others are new and clean versions of items previously available.
Power
Two new power generators have been added, the Vault-Tec Reactor and Vault-Tec Super Reactor. The new reactors offer a significant increase in power available and all old generators pale in comparison. The Vault-Tec Reactor produces 150 power while the Vault-Tec Super Reactor produces 500. The reactors require a lot of Nuclear Material to build but the vault provides plenty in the Uranium caves.
New Structures
You will find a selection of new vault-related structures at your disposal. Structures are grouped by categories and can be expanded for more pieces, such as a hallway or a corner, to fit your building needs. The new structures allow you to personalize the look of your vault with themed room components to build cafeterias, nurseries, quarters and more.
The structure categories include Atrium, Domestic, Room, Utility, Doors, Railings and Stairs and Supports.
Building Tips
The key to building is connecting doorways to doorways.
Use the doorway pieces within each vault subsection to connect different sections together.
If you're using the Atrium structures as the start of your vault, connect an Atrium doorway to a Room doorway. You will then be able to add to the rest of the room. If you have difficulties connecting an Atrium doorway to a Room doorway, use a Domestic doorway in between. Utility structures work the same as Domestic.
If you've used the Domestic doorways as a connector, you can delete the Domestic doorway once you have attached the two pieces.
Achievements
Vault Dweller
Equip a Vault 88 suit and Pip-Boy on a settler, and you'll receive 20 achievement points.
You can find Pip-Boys and vault suits in the Vault 88 trunk by the vault entrance. The Pip-Boy will auto-equip, but you will have to manually equip the vault suit.
Better Living Underground
Unlock all build areas of Vaut 88, and you'll receive 15 achievement points.
Oversight
Become Overseer, and you'll receive 15 achievement points.
If the Overseer stays after Lady Luck, you will not receive the Oversight achievement.