Sunset Overdrive

Sunset Overdrive (Insomniac Games, 2014 on Xbox One, 2018 on PC) is an open-world action game set in Sunset City, built on Insomniac’s engine at its i16 generation. The PC port is the one recorded here (made by Blind Squirrel according to the executable’s timestamp and credits; Steam app 847370). Observed

The observations come from one recorded census of the Steam build 3373500 (Sunset.exe, x64, PE timestamp 2018-12-06; about 28 GB installed). The install is no longer present, so the figures cannot be re-checked today. The counts are measurements over every asset of the stated kind and are marked Observed; nothing for this game is marked as proven. Observed

Where the data lives

<game folder>\
  Sunset.exe, commandline.txt   (-archive assets_archive\toc -warn review -fullscreen)
  assets_archive\toc            the compressed index of every asset
  assets_archive\g00s000 .. g05s000, a00s002.us .. a00s010.br    the 20 archives (global and localised)
  layout.csv, archive_input.json, chunkmap.txt, scan.csv         build leftovers the game does not use
  Houdini Engine, Alembic, OpenVDB, Bink 2 and Wwise runtime libraries

All Observed. The toc and the archives explains how the 399,775 assets are found and named.

The city

One level, levels/sunset_city/sunset_city.level, with the open world in hexagonal tiles hex_NNN (Zones): 1,422 zones of placements hold 953,948 placed models whose 4,711 distinct model paths resolve to 4,709 .model assets (Models). Collision is Havok hknp in .zone_physics assets (Havok collision). The minimap is a 4688 × 3364 BC7 texture (Textures). Observed

What is special about this game

• It is an older generation of Insomniac’s formats: 32-bit asset ids, a zlib-compressed toc with 114 spans and duplicated assets, and archives that are plain concatenations. Sourced · ALERT wiki
• Assets have no paths in the archive. Every one of the 399,775 gets its path from layout.csv, a build leftover. Observed
• Compressed assets are one LZ4 block over the DAT1 and its pixels together, so a reader must decompress to the DAT1 size plus the payload length. Observed
• The index flag of a mesh is inverted in ALERT’s OBJ writer: 0x10 means indices relative to the vertex start. Observed
• Collision is Havok hknp 2013.2.0-r1 with an empty types section, so shape layouts are not self-describing. Observed
• Traversal is authored in the zones (Grind, LedgePath, Mountable, Vaultable, UnderGrind, HorizontalPoleSwing, AllowHop strings), but the records are not decoded. Observed

Which build do the observations come from?

Steam build 3373500. Whether the census figures hold for other updates is not known.

What is known

System	Claims	Confidence	Proven or observed
Overview	13		69%
Archives and files	21		81%
Data model	30		53%
World and streaming	34		68%
Geometry	48		71%
Textures	36		83%
Collision and physics	24		83%

Computed from the engine's pages; the whole picture is on the coverage page.