Bethesda has announced that Fallout 4 is going subterranean with the newest piece of DLC, Vault-Tech Workshop. Because this is such a big addition to what you can do in the game, Bethesda held a Twitch Stream to go over some details, which you can watch below.
Build a brighter future underground with the all-new Vault-Tec Workshop. Create a massive Vault and attract new Dwellers using pre-war industrial kits complete with retro-nostalgic furniture, lighting, and art. And like every good Overseer, run Vault-Tec approved experiments on your Dwellers to learn what makes an ideal citizen. Vault-Tec has given you the tools, the rest is up to you!