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Oblivion Remastered (2025) — Engine, Containers & Animation Reference

Cross-reference: Legacy Gamebryo formats (BSA v104/v105, NIF, IMG/COL/CFA/DFA, EGM morphs, cell data, save files) → XeNTaX Bethesda knowledge §1,3,6–8,10–11

Oblivion Remastered (released 2025-04-22) is not a Havok title: it is a dual-engine hybrid. Unreal Engine 5.3 renders the game (models, textures, UI, audio, animation), while the original Gamebryo engine still runs core game logic (quests, AI, scripting, physics, combat). The Fallout 4/Skyrim .hkx behavior-animation ecosystem documented elsewhere in this hub does not apply here — this page collects verified facts about the engine split, the UE5 Io Store containers, the legacy Gamebryo data layer, the UE5-native animation pipeline, and the community tooling, and explicitly marks what is not yet confirmed.

1. Overview: A Hybrid Engine, Not a Havok Title​

  • Release: 2025-04-22 (PS5 / Windows / Xbox Series X|S); Switch 2 port on 2026-08-11. Development began 2021; co-developed by Virtuos (Paris) and Bethesda Game Studios. [HIGH — Wikipedia]
  • Renderer: Unreal Engine 5.3 (5.3.2 per community tooling; FModel's preset is GAME_UE5_3; animation modding requires compiling UE 5.3.2 source). Uses UE5's Lumen dynamic lighting and ray tracing. [HIGH — multiple sources]
  • Game logic: the original Gamebryo engine is still used to handle core game logic — quests, AI, scripting, physics, combat. [HIGH — UESP]
  • Consequence for modders: there are two asset pipelines — UE5 .pak assets for presentation, and the legacy Gamebryo Data/plugin layer for logic. Original game data (ESM/BSA/NIF) was re-authored as UE5 assets for rendering; BSA/NIF are ignored at runtime.
  • Why the FO4 guide does not apply: 2006 Oblivion used Gamebryo .kf/.nif animation (.hkx behavior files only arrived with Skyrim/FO4). The remaster ignores NIF entirely; the original animation files are not loadable. There is no Havok hkx anywhere on the UE5 side. [HIGH]
  • The Gamebryo core is reported as updated to 64-bit stable. [MEDIUM — secondary source]

2. Content Containers & File Structure​

UE5 side — Io Store paks​

  • Install layout: \Steam\steamapps\common\Oblivion Remastered\OblivionRemastered\Content\Paks holds all .pak files. [HIGH]
  • Main package: OblivionRemastered-Windows.pak — all new sounds, code, and most content. [HIGH]
  • Container format: UE5 Io Store — each archive is a triple of .pak + .utoc + .ucas; mod managers must list/delete all three, and repacking .utoc requires the retoc tool. Assets inside are .uasset/.uexp. [HIGH]
  • Browsing paks in FModel needs a usmap mappings file and the GAME_UE5_3 preset. No entry exists in TheNaeem/Unreal-Mappings-Archive; the community standard is huwiee's usmap. [HIGH]
  • Compression is not explicitly confirmed as Oodle; UE 5.3 Io Store defaults to Oodle — verify from the .pak/.utoc header or FModel. [MEDIUM]

Legacy Gamebryo side — Data folder & plugins​

  • Legacy Data lives at Content\OblivionRemastered\Content\Dev\ObvData\Data (contains the ESMs/ESPs and Plugins.txt; the Generate Plugins.txt Loader regenerates Plugins.txt there). [MEDIUM — gist, corroborated by forum posts]
  • The original ESM/ESP plugins are byte-identical to the 2006 release; the only exception is DLCHorseArmor.esp (one dirty message). Remaster changes ship via 3 new ESPs: AltarESPMain.esp, AltarDeluxe.esp, AltarESPLocal.esp. [HIGH — UESP]
  • Localization: every ESM/ESP record's Full Name was replaced by a unique UE5 string-table key; unkeyed mod records show a [NL] prefix, unresolved keys show <MISSING STRING TABLE ENTRY>. [HIGH]
  • Console: the UE5 console replaces the classic console; legacy commands need the obvConsole prefix (e.g. obvConsole tgm), and some Gamebryo commands (e.g. tcl) are inert. [HIGH]
  • Audio: Wwise; sounds ship as .wem under Content\WwiseAudio\Media, referenced via MediaPathName (e.g. Media/94211525.wem); new sounds live under OblivionRemastered/Content/WwiseAudio/Interface/.... [HIGH]

3. Animation & Physics​

UE5-native animation — not Havok behavior graphs​

  • Animation is UE5 native (Animation Sequences / Skeletal Meshes). The workflow is: import FBX into a UE 5.3.2 project → asset becomes a .uasset → package into a .pak with Io Store. No hkx anywhere. [HIGH]
  • Prerequisites (per the official-style animation article): ~200 GB free disk, Blender 4.2 LTS, UE 5.3.2 source, Visual Studio 2022 (C++ workload), the Oblivion Remastered sample project, and FModel. [HIGH — Nexus article 141]
  • Naming/paths example: A_Humanoid_OneHand_Sprint.fbx lands in Content/Art/Animation/Humanoid/ThirdPerson/OneHanded/Locomotion/Normal. [HIGH]
  • Skeleton: SKEL_HumanoidSkeleton — its virtual bones are IK leg targets; the humanoid rig FBX is SK_HumanoidFull.fbx. [HIGH]
  • Lip-sync is an entirely new system. [HIGH]

Physics — legacy Gamebryo era​

  • Physics are the exact same as the original Oblivion: gravity is slightly heavier with less ragdolling, and physics-enabled objects settle immediately on cell load. [HIGH — Steam discussion + UESP]
  • There is no Havok on the UE5 side; the Gamebryo side retains the legacy (Havok-era) physics stack — but Oblivion physics were never the hkx behavior system anyway. [MEDIUM — inference]

4. Modding Tools​

ToolRoleSource
FModelBrowse/extract UE assets from paks; needs huwiee usmap + GAME_UE5_3https://fmodel.app/ ; https://www.nexusmods.com/oblivionremastered/mods/47
UnrealPak (FluffyQuak)Pack/unpack .pak (drag folder onto UnrealPak-With-Compression.bat / UnrealUnpak.bat)https://github.com/Dmgvol/UE_Modding/blob/main/BasicModding/UnrealPak.md
UE4SS for OblivionRemasteredLua scripting loader/injector for the UE sidehttps://www.nexusmods.com/oblivionremastered/mods/32
UE4SS TesSyncMapInjectorSyncs .esp form IDs with the UE runtime (no pak needed); Smart Mapper varianthttps://www.nexusmods.com/oblivionremastered/mods/1272 ; /2784
OBSE64Oblivion Remastered Script Extender (engine-level)https://raw.githubusercontent.com/KelpyCode/oblivion-remastered-modding-wiki/main/create.md
xEdit → TES4REdit.exePlugin editor; rename the xEdit exe to load remaster pluginshttps://forums.nexusmods.com/topic/13515989
Construction Set v1.2Legacy plugin editing still works for the data layerhttps://cs.uesp.net/wiki/The_Elder_Scrolls_Construction_Set
MagicLoader + MagicPatcherNew interior cells; generates .json confighttps://www.nexusmods.com/oblivionremastered/mods/1966 ; /2906
nathtest/UProjOblivionRemasteredUE 5.3.2 project derived from a UE4SS dump; blueprint-modding base (needs ENGINE_API fix in InputDeviceProperties.h)https://github.com/nathtest/UProjOblivionRemastered
Blueprint Mod Loader / Simple Mod LoaderLoad blueprint .pak modshttps://www.nexusmods.com/oblivionremastered/mods/2610
retoc + uAssetGUIRepack .utoc; edit .uasset; mods load if named alphabetically before Oblivion paks (e.g. 000_Mod.pak)https://www.nexusmods.com/oblivionremastered/mods/3918
Plugins and Paks ManagerPlugin + pak management GUIhttps://www.nexusmods.com/oblivionremastered/mods/446
Generate Plugins.txt LoaderPowerShell Plugins.txt generatorhttps://www.nexusmods.com/oblivionremastered/mods/283
WwiseConvert .wav → .wem for sound modshttps://www.audiokinetic.com/en/
MO2 dev buildMod Organizer 2 build with remaster support (Discord)https://discord.gg/ewUVAqyrQX
NIF→FBX converterDaggerfallTeam (Patreon, not free)https://www.patreon.com/DaggerfallTeam/posts/nif-to-fbx-for-128457165

Mod naming rule: pak mods go in a folder named OblivionRemastered-Windows_<mod>_P and the .pak file must end in _P for MO2/Vortex to load it. [HIGH]

5. Community Resources​

ResourceURLNotes
Nexus Mods game pagehttps://www.nexusmods.com/oblivionremasteredOfficial mod hosting
Oblivion Remastered Modding Wikihttps://github.com/KelpyCode/oblivion-remastered-modding-wiki (site: oblivion.wiki)Tooling (create.md); FAQ page currently empty
Modding Discordhttps://discord.gg/4FJEEsmDSy ; https://oblivion.wiki/discordGuides, tech support
UESPhttps://en.uesp.net/wiki/Oblivion:Oblivion_Remastered ; Remastered Changes ; Remastered CombatCanonical gameplay/technical change list
Steam store pagehttps://store.steampowered.com/app/2623190/App ID 2623190; active discussions
Nexus forums tools/tutorials listhttps://forums.nexusmods.com/topic/13515989Curated tool + tutorial index
Full modding guide (video)https://www.youtube.com/watch?v=Kv-iOPHuOiEBlender + UE5 mesh/texture pipeline

6. Open Questions & Unconfirmed Details​

  • Pak compression: Oodle is likely (UE 5.3 Io Store default) but was not confirmed from the .pak/.utoc header — verify with FModel. [MEDIUM]
  • usmap completeness: the community usmap (huwiee, Nexus mods/47) works with FModel, but no mapping exists in TheNaeem/Unreal-Mappings-Archive; coverage of all classes is unverified.
  • Gamebryo 64-bit update rests on a single secondary source. [MEDIUM]
  • "No Havok on the UE5 side" is an inference from the animation pipeline and container contents, not a Bethesda statement. [MEDIUM]
  • The Wakui tecblog UE 5.3.2 animation-replacement guide (https://wakui-tecblog.chimpoy.click/modding-oblivion-remastered-in-ue-5-3-2-a-guide-to-replacing-animations/) could not be fetched at research time (connection error).

7. Sources​