File Format Overview

NRS games use a custom engine derived from UE3. Assets are stored as compressed .xxx packages containing a Midway-format UPK.

Common Elements

All games share:

• Magic: 0x9E2A83C1 (UE3 standard)
• Block compression: Oodle codec with 128KB chunk size
• Table structure: Name table (string pool) + Import table (external refs) + Export table (objects)
• Property system: UE3 serialized properties (StrProperty, IntProperty, StructProperty, etc.)

Per-Game Formats

See the detailed format pages:

• Injustice 2 Format — 100-byte header, flat compressed chunks, TFC textures, Verified structs
• MK11 Format — 104-byte header, named packages, PSF external data

Header Identification

Offset 0x00: Magic (u32) = 0x9E2A83C1
Offset 0x04: FileVersion (u16) — identifies the engine version
Offset 0x0C: MidwayTeamFourCC (char[4]) — game identifier

Game	FileVersion	FourCC	BranchVersion
IJ2	732 (0x2DC)	DCF2	DDEV
MK11	769 (0x301)	MK11	MAIN

Table Entry Comparison

Field	MK11 Export (76B)	IJ2 Export (72B)
ClassIndex	i32 resolve	i32 resolve
SuperIndex	i32 resolve	i32 resolve (at pos 2, not 5)
OuterIndex	i32 resolve	i32 resolve (at pos 3, not 2)
ObjectName	FName (i32+u32)	FName (u32+u32)
ArchetypeIndex	—	i32
ObjectFlags	u64	u64
GUID	16 bytes	16 bytes
Size+Offset	u32+u64	u32+u64
ComponentMap	—	u32 count + entries
ExportFlags	—	u32

See Format Comparison for the full side-by-side analysis.