Here's some information on the engine from Wiki:
Fallout 4 uses Bethesda's Creation Engine, which was created for The Elder Scrolls V: Skyrim.[22] Just after Fallout 3's release, the team devised numerous design objectives to meet for Skyrim—which were updated for Fallout 4's hardware requirements. The updated Creation Engine allows for numerous improvements in graphical fidelity over Bethesda's previous efforts. For instance, the draw distance renders much farther than previous Fallout games; in an interview on the engine for Skyrim, Howard provided an example where the player can stare at a small object such as a fork in detail, and then look up at a mountain and run to the top of it.[citation needed]
Dynamic lighting allows shadows to be created by any structure or item in the game world. Howard revealed in the E3 Press Conference[when?] that the updated Creation Engine allows for next-generation god rays and advanced volumetric lighting.[vague] The updated engine features a variety of visual effects not present in previous Bethesda games such as motion blur, temporal anti-aliasing, height fog, dynamic dismemberment, screen space reflections, filmic tone mapping, an updated material system—for wet textures—among numerous others.[23][weasel words] The updated engine allows the Bethesda team to add more dynamic lighting to every scene as well as "paint surfaces with realistic materials".[24] Bethesda released an example on how the updated engine works: "When a rain storm rolls in, our new material system allows the surfaces of the world to get wet, and a new cloth simulation system makes cloth, hair, and vegetation blow in the wind."[25]
The updated Creation Engine allows for a more advanced character creation system, which utilizes sculpting—forgoing the series of sliders present in previous games. In detail, the new character creation system introduces a new, freeform, entirely slider-free facial editor controlled via dynamic, real-time modelling interface.[26] The updated engine allows for more fluid animations designed for next-generation hardware.[citation needed]
With regards to the aforementioned fluid animations, the updated engine also allows a much more open approach to conversations with NPCs—wherein the camera views can change depending on the player's preference from a first person view to a cinematic third person view—compared to Fallout 3's rigid and instanced conversation system. The protagonist features dynamic dialog, which is context sensitive, and allows players to back out of a conversation. In Howard's words, "you are free to walk away anytime if you want, or you can even shoot him in the face."[27]