I.G.I. 2: Covert Strike (2003) — File Formats Architecture

1. The Architectural Evolution of I.G.I. 2

Released in 2003, I.G.I. 2: Covert Strike has format guides covering scripts, resources, models, terrain, vegetation, audio, and synchronization data. Engine behavior is included only where linked implementation or research supports it.

The IGI 2 guide index includes resource and model files, terrain-related formats (.thm, .tlm, .tmm), vegetation data, and synchronization data. Similar extensions across games do not by themselves establish identical internal layouts.

2. Index of 19 IGI 2 Format-Guide Topics

3. Format families

This diagram groups the guide topics by their documented role. It is an index, not a claim about runtime load order.

4. Key Structural Differences from IGI 1

• MEF Type 3 (MODEL_LIGHTMAP): The IGI 2 template and parser use a 28-byte XTRV record; the IGI 1 layout uses 40 bytes. The longer reference document in the converter repository disagrees and needs retail-sample confirmation.
• Collision Faces (ECFC): The IGI 2 parser reads 12-byte records: three 16-bit indices, a 16-bit material field, and two additional 16-bit fields. Their exact engine meanings are not established here.
• OLM Object Lightmaps: The research notes describe version values 0.10 (IGI 1) and 0.16 (IGI 2), with single-layer IGI 1 files and one- or three-layer IGI 2 files.
• Terrain guides: IGI 1 and IGI 2 use different documented terrain extensions; consult each format guide for its evidenced fields.
• MEF differences: See the MEF guide for the current parser and template layouts, including the unresolved conflict in the longer reference document about the IGI 2 Type 3 vertex stride.