''Fallout 4'' is set in a [[Apocalyptic and post-apocalyptic fiction|post-apocalyptic]] [[Boston]] in the year 2287, 210 years after a devastating nuclear war, in which the player character emerges from an underground bunker known as Vault 111. Gameplay is similar to that of ''[[Fallout 3]]'' and ''[[Fallout: New Vegas]]''. The player completes various quests and acquires experience points to level up their character. With [[First-person shooter|first-person]] and [[Third-person shooter|third-person perspectives]] available, players can explore ''Fallout 4''{{'}}s open world setting at will, allowing [[nonlinear gameplay]]. The player can bring companions to assist in battles and help with scavenging. Players have the ability to construct and deconstruct buildings and items, and use them to build settlements, which can attract and be inhabited by [[non-playable characters]].

The game was rumored several times prior to its announcement. It was announced on June 3, 2015. The first gameplay footage of the game was shown at Bethesda's own conference at the [[Electronic Entertainment Expo 2015|2015 Electronic Entertainment Expo]]. It is the first game in the series to feature full voice acting for the protagonist.

''Fallout 4''{{'}}s gameplay is similar to that of ''[[Fallout 3]]'' and ''[[Fallout: New Vegas]]'', the previous two main entries in the series. Returning features include a camera that can switch between a [[First person (video games)|first-person]] and [[Third-person view|third-person]] perspective, and the ability to roam anywhere on the map. ''Fallout 4'' introduces new features including a layered armor system, base-building, a dynamic dialogue system featuring 111,000 lines of dialogue,<ref>{{cite web|url=http://www.gameinformer.com/b/news/archive/2015/09/05/bethesda-completes-recording-of-fallout-4-39-s-111-000-lines-of-dialogue.aspx|title=Bethesda Completes Recording Of Fallout 4's 111,000 Lines Of Dialogue|first=Kyle|last=Hilliard|date=September 5, 2015|accessdate=October 19, 2015|work=[[Game Informer]]}}</ref> an in-depth crafting system which implements every lootable object in the game, and much more. Enemies such as mole rats, raiders, super-mutants, deathclaws, and feral ghouls return in ''Fallout 4'', along with the companion [[Dogmeat]].<ref>{{cite web|url=http://www.pcgamer.com/fallout-4s-dogmeat-cannot-be-killed/|title=Fallout 4's Dogmeat cannot be killed|first=Andy|last=Chalk|work=[[PC Gamer]]|date=June 17, 2015|accessdate=June 17, 2015}}</ref>

Players have the ability to roam anywhere on the map, and leave a conversation at any time. They have the ability to customize weapons; the game includes over 50 base guns, which can be crafted with a variety of modifications, such as barrel types and laser focus, with over 700 modifications available. Power Armor has been redesigned to be more like a vehicle than an equipable suit of armor,<ref name="Fo4 Trailer">{{cite AV media |people=Bethesda Softworks |date=June 15, 2015 |title=Fallout 4 – E3 Showcase World Premiere |medium=YouTube |url=https://www.youtube.com/watch?v=GE2BkLqMef4 |access-date=June 28, 2015 |publisher=[[Bethesda Softworks]]}}</ref> and can be modified, allowing players to add items such as a jetpack or selecting separate types of armor for each part of the suit.<ref>{{cite web|url=http://www.pcgamer.com/fallout-4-screenshots-and-art-show-customisation-mutants-more/|title=Fallout 4 screenshots show jetpacks, mutants, more|last=Sykes|first=Tom|date=June 15, 2015|accessdate=June 15, 2015|work=[[PC Gamer]]}}</ref> A new feature to the series is the ability to craft and deconstruct settlements and buildings. Players can select some in-game objects and structures, and use them to freely build their own structures. In addition, the towns can be powered with working electricity, using a dynamic power line system. Merchants and [[non-player character]]s can inhabit the player's settlements, for which the player must provide sustenance by growing food in makeshift patches and building water spouts. Players can build various defenses around their settlements, such as turrets and traps, to defend against random attacks.<ref name="crafting">{{cite web|url=http://kotaku.com/fallout-4s-crafting-system-is-bonkers-1711322298|title=Fallout 4's Crafting System Looks Awesome|last=Hernandez|first=Patricia|date=June 14, 2015|accessdate=June 15, 2015|work=[[Kotaku]]}}</ref>

The Pip-Boy, a personal computing device strapped to the character's wrist, allows the player to access a menu with statistics, maps, data, and items. Players can find game cartridges, which can be played on the Pip-Boy. Another returning gameplay feature is the Vault-Tec Assisted Targeting System (V.A.T.S.), which plays an important part in combat. While using V.A.T.S., real-time combat is slowed down, and action is played out from varying camera angles in a computer graphics version of "[[bullet time]]". Various actions cost action points, limiting the actions of each combatant during a period of time, and the player can target specific body parts for attacks to inflict specific injuries; head shots can be used for quick kills or blinding, legs can be targeted to slow enemy movement, and opponents can be disarmed by shooting at their weapons. Unlike previous games, in which the player had a random chance to inflict a critical hit, they are now performed manually through V.A.T.S.<ref name="First Gameplay">{{cite web|url=http://ign.com/articles/2015/06/15/e3-2015-fallout-4s-first-gameplay-and-story-details|title=E3 2015: Fallout 4's First Gameplay Details|last=Ingenito|first=Vince|work=[[IGN]]|publisher=[[Ziff Davis]]|date=June 14, 2015|accessdate=June 21, 2015}}</ref>