Modding

Source: 298b3e8f49b4. Check the source page for feature scope.

Modding LostOdysseyRecomp

These pages describe the mod system as of v0.9.52: mod format v1 and v2 (mod folders with their own overlay files).

4x HD texture pack

About 15,400 of the game's textures, upscaled 4x. Windows only, like all mods; it needs v0.9.22 or later. The download is 16.4 GB in four parts and unpacks to 33 GB.

1. Join the Discord server, open the #mods forum and find the 4x HD Texture Pack v1.0 post. Its download link has five files; download all of them into one folder: LostOdysseyRecomp-HD-Textures-4x-v1.0.7z.001 to .004, and SHA256SUMS.txt.
2. Optional: check the downloads. Open PowerShell in that folder and run Get-FileHash *.7z.* -Algorithm SHA256. Each hash must match the line for that file in SHA256SUMS.txt.
3. Install 7-Zip if you don't have it.
4. Right-click LostOdysseyRecomp-HD-Textures-4x-v1.0.7z.001 and choose 7-Zip → Extract files.... As the destination, pick your game folder: the folder that contains LostOdysseyRecomp.exe. 7-Zip reads the other three parts by itself.
5. Check that the game folder now contains mods\hd-textures-4x\mod.ini.
6. Start the game. Settings → System → Mods lists 4x HD Texture Pack, turned on.

After step 5 you can delete the four .7z files.

Problem	Fix
7-Zip reports a missing volume or an unexpected end of archive.	One part is missing or incomplete. Download all four parts into the same folder, then check them with step 2.
The textures look unchanged.	The folder must be mods\hd-textures-4x\ directly next to LostOdysseyRecomp.exe, not mods\mods\.... Check that the pack is on in Settings → System → Mods. A pack copied in while the game runs appears after a restart.
Short stutters when entering an area for the first time.	The game reads the new textures from disk as they are needed. Keep the game folder on an SSD.

To remove the pack, delete mods\hd-textures-4x\, or turn it off in Settings → System → Mods.

What works today

Resource or feature	Status
Native settings-menu UI_MAIN_00 atlas	Replacement is wired into settings/menu_assets.cpp; preserve the original 512x1024 dimensions and layout. See Creating mods.
Texture pages used by native menu fonts	Image replacement is wired at the same decoder; preserve each page's dimensions and glyph positions. Font metrics are unchanged.
Textures drawn by the game	Replaced at upload by fingerprint from .lotex2 files, at the original size or 2x/4x/8x larger (experimental; uncompressed RGBA8 or BC1, BC3, BC4 or BC7 DDS). See Creating mods and Modding API.
Game text	Translations replace the game's text by key from the JSON files the export writes, including longer text (experimental). A language pack adds a new choice to Settings → System → Game language. See Creating mods.
Cutscene videos (movies)	Replace a cutscene picture with an H.264 MP4 named after the original video (overlay/movies/mv_00v.mp4). Windows only for now; see Creating mods.
Models	Character, monster and moving-object models (SkeletalMesh) and map pieces (StaticMesh, StaticMeshRPG), as glTF (.glb) edited from the export, keeping the original skeleton and material names; a map's baked lighting follows a new map piece. See Creating mods. Animations are not replaceable.
Letters the fonts lack	A language pack can add glyphs to the game's fonts, drawn from a TrueType or OpenType font with lo_mod.py font-glyphs, for languages such as Polish, Russian or (with pre-shaped text) Arabic. See Creating mods. Replacing whole font files or metrics is not supported.
Mod folders	One folder per mod: mods/<id>/mod.ini with a name, version and author, plus its own overlay/ files found by name. The order in mod-list.ini (next to settings.ini), then priority, decides between mods. Settings → System → Mods turns mods on or off and changes their order. See Creating mods.
External manager overlay	Deterministic top-level overlay/ paths that a manager orders, and an isolated resolution mode.
Exporting original artwork	LostOdysseyRecomp.exe --export-assets <folder> writes your game's textures (PNG plus index.csv with mod keys and fingerprints), movies and text (JSON per game text file, the starting point for translations). With --export-kinds models,animations it also writes 3D models and animation sets as glTF (.glb); edited character models can go back into a mod. Also available from an MO2 tool. See Creating mods.
Overlay archives	A mod folder can hold its overlay/ files in one overlay.loarc archive instead of thousands of loose files, made with lo_mod.py archive. See Creating mods.
Rebuilt game files	Files that replaced models or translations rebuild once, then are kept compressed in cache/mods; a window shows Preparing mods while this runs. See Creating mods.
Mod Organizer 2	The game plugin and export tool are in the Windows ZIP's mo2 folder (source: tools/modding/mo2); MO2 maps mods onto mods/. See Mod Organizer 2.

Mods do not modify LO.fpi, FPD archives or other imported game files. Mod packages contain data, not automatically loaded native libraries.

Supported platforms

Mods are supported on the Windows build only. The Linux, macOS and Android builds read the same mods/ folder, but mods are untested and unsupported there. A GPU that cannot sample BC-compressed textures skips BC texture replacements and keeps the original texture.

Start here

• Creating mods: texture packs, translations and language packs, settings-menu artwork, and how to install them.
• Mod Organizer 2: MO2 setup, the export tool, and which mod wins.
• Open models in Blender: look at exported models and play their animations.
• Modding API: identities, resolution, the file formats and extension points.
• Asset inventory: the read-only four-disc resource catalog and its counting limits.
• Runtime texture replacement: what texture replacement covers and what is still open.
• Validation: the automated checks and the game and MO2 acceptance steps.

Installation essentials

The portable layout uses mods/ next to the executable. Other layouts use the application's data directory plus mods/. Set LO_MODS_DIR to an absolute path to choose an explicit root. In the game, Settings → System → Mods → Open mods folder (Windows) opens it. ZIPs produced by the packer contain a top-level mods/ folder (mods/<id>/... for a mod folder); deploy the contents of that folder into the selected root, without adding another mods/ level.

With Mod Organizer 2, install packages through MO2 instead; see Mod Organizer 2. Restart after installing or removing mods, or after editing mod-list.ini by hand. Settings → System → Mods turns mods on or off and changes their order; saving applies the list while the game runs: textures at once, replaced models from the next area you enter (party members after a restart). There is no file watcher. LO_MODS=0 disables every replacement, including trusted providers.

Use only artwork you may distribute. Do not bundle the original game archives, executable, extraction catalog or unrelated extracted artwork with a mod.