Unreal Engine
Unreal Engine 5 keeps a game’s cooked content in packages (.uasset, .uexp, .ubulk), which a shipped game stores inside
containers rather than as loose files. The games documented here are MECCHA CHAMELEON (Steam app 4704690, Unreal Engine 5.6.1,
executable PenguinHotel, project Chameleon) Sourced · Unreal Engine source and
Phantom Blade Zero (Steam app 4115450, project ProjectPBZ), whose containers are
encrypted. Observed · PBZ
| Area | What the games ship | Page | Confidence |
|---|---|---|---|
| content container | IoStore: a .utoc table of contents (version 8, flags 0x09: compressed, indexed, unencrypted, unsigned) with a .ucas data file, Oodle-compressed in 64 KiB blocks |
IoStore containers | Proven · MECCHA |
| global data | a second container, global, with one script-objects chunk |
IoStore containers | Proven · MECCHA |
| other files | a version 11 pak | IoStore containers | Observed · MECCHA |
| encrypted containers | Phantom Blade Zero: IoStore container flags 0x0b (encrypted, 66 partitions of 2 GiB) and version 12 paks with encrypted indexes | IoStore containers | Proven · PBZ |
| user maps | a content-only plugin with one World Partition level, cooked as a DLC and shipped as a Steam Workshop item | custom maps | Observed · MECCHA |
The game ships plugins for Steam Workshop maps and for mod.io user content, with its Epic Online Services integration and Mocopi live-link plugin; its cooked content is not encrypted or signed, so the containers can be read as they are. Observed · MECCHA
The packages inside the containers (the export bundle layout, the class registry of Unreal 5.6, materials, meshes and levels as this game cooks them) are not described here; only the container level and the custom-map route are.
Pages
Archives and files
- IoStore containers (.utoc and .ucas) and pak files — Unreal Engine 5's container format as MECCHA CHAMELEON and Phantom Blade Zero ship it: the .utoc table-of-contents header (version 8), its arrays, chunk ids and types, compression blocks, flags, partitions, encryption, and the accompanying pak files.
Mod loading
- Custom maps for MECCHA CHAMELEON — How the game loads player-made maps: the official mod kit, the content-only plugin a map is, its level and collision requirements, packaging as a cooked DLC, and the Steam Workshop route.