This folder contains documentation for LEGO Island's custom binary file formats using Kaitai Struct, a declarative language for describing binary data structures.

What is Kaitai Struct?

Kaitai Struct allows you to define binary formats in a YAML-based .ksy file, which can then be:

Compiled into parser libraries for many programming languages (C++, Python, JavaScript, etc.)
Visualized interactively using the Kaitai Struct Visualizer
Dumped to human-readable formats using ksdump

Documented Formats

File	Extension	Description
`savegame.ksy`	`.GS`	Main game save data (game state, progress, customizations)
`players.ksy`	`.gsi`	Player profile save data (usernames)
`history.ksy`	`.gsi`	Score history and high scores
`animation.ksy`	`.ani`	Animation data (keyframes, actor references, camera animation)
`wdb.ksy`	`.wdb`	World database (textures, parts, models, ROI hierarchies, LODs)
`dta.ksy`	`.dta`	Animation data (world animation info, model placement)

Using the Tools

Installation

See the Kaitai Struct Visualizer installation instructions for setup details.

Kaitai Struct Visualizer (ksv)

The Kaitai Struct Visualizer (ksv) provides an interactive terminal UI for exploring binary files.

# View a save game file
ksv samples/G0.GS savegame.ksy

# View a Players.gsi file
ksv samples/Players.gsi players.ksy

# View a History.gsi file
ksv samples/History.gsi history.ksy

# View an animation file
ksv samples/pns065rd.ani animation.ksy

# View the world database (from game installation)
ksv /path/to/lego/data/world.wdb wdb.ksy

# View an animation data file
ksv samples/BLDRINF.DTA dta.ksy

Kaitai Struct Dump (ksdump)

ksdump outputs the parsed structure as JSON or YAML for scripting and inspection.

# Dump a save game to JSON
ksdump --format json samples/G0.GS savegame.ksy

# Dump Players.gsi to JSON
ksdump --format json samples/Players.gsi players.ksy

# Dump History.gsi to YAML
ksdump --format yaml samples/History.gsi history.ksy

# Dump an animation file to JSON
ksdump --format json samples/pns065rd.ani animation.ksy

# Dump world database to YAML (from game installation)
ksdump --format yaml /path/to/lego/data/world.wdb wdb.ksy

# Dump an animation data file to JSON
ksdump --format json samples/BLDRINF.DTA dta.ksy

Sample Files

The samples/ directory contains example files for testing:

G0.GS, G1.GS, G2.GS - Sample main game save files (slots 0, 1, 2)
Players.gsi - Sample player profile data
History.gsi - Sample score history data
pns065rd.ani - Sample animation file
BLDRINF.DTA - Sample animation data file

Note: The world database (world.wdb) can be found in your LEGO Island installation at lego/data/world.wdb.