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Papyrus

Papyrus is the scripting language used by the Creation Engine to implement gameplay logic. It handles quests, encounters, perks, magic effects, AI packages, scripted events, and UI behavior. Scripts are compiled to bytecode (.pex) and executed by a virtual machine integrated into the engine.

Papyrus was introduced in The Elder Scrolls V: Skyrim (2011) as the successor to Oblivion's Obscript. Fallout 4 uses an extended version of the same language and runtime.

Source files

The Creation Kit installation includes the full Papyrus source code for the game in .psc format, located at:

./Fallout 4/Data/Scripts/Source/

Source files are organized into subdirectories by content origin: Base for the base game, DLC01 through DLC06 for the official DLCs, and separate folders for Creation Club content.

Script counts

Source Scripts
Base game 7,859
DLC01 — Automatron 483
DLC02 — Wasteland Workshop 43
DLC03 — Far Harbor 830
DLC04 — Nuka-World 908
DLC05 — Contraptions Workshop 40
DLC06 — Vault-Tec Workshop 92
Total 10,255

Compilation

.psc source files are compiled to .pex bytecode files, which are what the engine actually loads at runtime. Compiled .pex files for the shipping game are packed inside Fallout 4 - Misc.ba2.