ArcNET

Read/write SDK for Arcanum: Of Steamworks and Magick Obscura game data formats. Span-based, zero-allocation binary parsing with a UI-agnostic library API — usable from console tools, Avalonia editors, Blazor WASM, and anything in between.

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Packages · Quick Example · Example Catalogue · Public API

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Packages

Package	NuGet	Status	Description
ArcNET.Core		✅ Ready	SpanReader / SpanWriter, primitive types (Location, ArtId, Color, GameObjectGuid, PrefixedString)
ArcNET.GameObjects		✅ Ready	Full game-object model — 22 typed data classes with explicit Read + Write
ArcNET.Formats		✅ Ready	Binary format parsers/writers for MES, SEC, ART, DLG, SCR, PRO, MOB, JMP, FAC, TDF, GSI, TFAI, TFAF, PRP
ArcNET.Archive		✅ Ready	DAT archive pack / unpack backed by MemoryMappedFile; TFAF sub-archive support
ArcNET.GameData		✅ Ready	GameDataLoader (MES, SEC, PRO, MOB wired; per-source origin tracking), GameDataStore with dirty tracking + GUID index + *BySource maps, GameDataSaver (preserves file origins), GameDataExporter (AOT-safe JSON)
ArcNET.Patch		✅ Ready	HighRes patch configuration, installer, and uninstaller
ArcNET.Dumpers		✅ Ready	Human-readable text dumpers for all game data formats (MES, SEC, ART, DLG, SCR, PRO, MOB, JMP, FAC, TDF, GSI, TFAI, TFAF, PRP)
ArcNET.BinaryPatch		✅ Ready	JSON-driven binary patching for bug fixes and mod authoring — field-level PRO/MOB mutations and raw byte patches with backup/revert/verify
ArcNET.Editor		✅ Ready	Save-game editing pipeline (LoadedSave, SaveGameEditor, SaveGameLoader, SaveGameWriter) for player and .gsi metadata edits, plus fluent builders (MobDataBuilder, CharacterBuilder, DialogBuilder, SectorBuilder, ScriptBuilder)

All packages target net10.0, carry no dependencies outside the BCL, and are AOT / trim compatible.

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Quick Example

using ArcNET.Formats;

// Parse a MES message file from disk — one allocation (File.ReadAllBytes)
MesFile mesFile = MessageFormat.ParseFile("arcanum/mes/game.mes");
IReadOnlyList<MessageEntry> messages = mesFile.Entries;

// Or from a buffer you already own — zero extra allocations
ReadOnlyMemory<byte> buf = await File.ReadAllBytesAsync("game.mes");
mesFile = MessageFormat.ParseMemory(buf);

// Serialize back to bytes
byte[] bytes = MessageFormat.WriteToArray(in mesFile);

For more examples see the Example Catalogue.

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Example Catalogue

The docs/examples.md file contains copy-paste-ready examples for every library and format:

• ArcNET.Formats — MES, SEC, ART, DLG, SCR, PRO, MOB, JMP, FAC, TDF, GSI, TFAI, TFAF, PRP parsers; round-trip serialization; file discovery
• ArcNET.Archive — open, enumerate, extract single/all entries, read without extracting, pack a directory, TFAF sub-archive
• ArcNET.GameObjects — read full game objects, read headers only, GameObjectStore
• ArcNET.GameData — load MES/SEC/PRO/MOB from directory or in-memory buffers (per-source origin tracking), save to disk / memory restoring original filenames, dirty tracking, AOT-safe JSON export
• ArcNET.Patch — install / uninstall the HighRes patch, read and modify HighResConfig
• ArcNET.Dumpers — human-readable text dumps for all parsed formats (mob, proto, sector, art, dialog, script, message, etc.)
• ArcNET.BinaryPatch — JSON-driven binary patching: field-level PRO/MOB mutations, raw byte offsets, backup/revert/verify, patch state tracking
• ArcNET.Editor — save-game round-trip: load a save slot into LoadedSave, inspect and mutate parsed mobiles / sectors / scripts, edit the player or .gsi metadata via SaveGameEditor, and write back with SaveGameWriter; fluent MobDataBuilder, CharacterBuilder, DialogBuilder, SectorBuilder, and ScriptBuilder for constructing or editing objects
• ArcNET.Core — low-level SpanReader / SpanWriter, primitive round-trips, EnumLookup

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Package dependency graph

ArcNET.App (exe)
  ├── ArcNET.BinaryPatch
  │     ├── ArcNET.Formats
  │     │     ├── ArcNET.GameObjects → ArcNET.Core
  │     │     └── ArcNET.Core
  │     └── ArcNET.Archive → ArcNET.Core
  ├── ArcNET.Dumpers
  │     ├── ArcNET.Formats  (→ see above)
  │     ├── ArcNET.GameObjects → ArcNET.Core
  │     └── ArcNET.Archive  → ArcNET.Core
  ├── ArcNET.Editor
  │     ├── ArcNET.GameData
  │     │     ├── ArcNET.Formats  (→ see above)
  │     │     ├── ArcNET.GameObjects → ArcNET.Core
  │     │     └── ArcNET.Core
  │     ├── ArcNET.Formats  (→ see above)
  │     ├── ArcNET.GameObjects → ArcNET.Core
  │     └── ArcNET.Archive  → ArcNET.Core
  ├── ArcNET.GameData
  │     ├── ArcNET.Formats  (→ see above)
  │     ├── ArcNET.GameObjects → ArcNET.Core
  │     └── ArcNET.Core
  ├── ArcNET.Archive  → ArcNET.Core
  └── ArcNET.Patch    → ArcNET.Core

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Building

dotnet tool restore
dotnet build ArcNET.Build.slnx -c Release

Testing

TUnit tests use the Microsoft Testing Platform runner:

dotnet run --project src/Core/ArcNET.Core.Tests -c Release
dotnet run --project src/GameObjects/ArcNET.GameObjects.Tests -c Release
dotnet run --project src/Formats/ArcNET.Formats.Tests -c Release
dotnet run --project src/GameData/ArcNET.GameData.Tests -c Release
dotnet run --project src/Archive/ArcNET.Archive.Tests -c Release
dotnet run --project src/Patch/ArcNET.Patch.Tests -c Release
dotnet run --project src/BinaryPatch/ArcNET.BinaryPatch.Tests -c Release
dotnet run --project src/Editor/ArcNET.Editor.Tests -c Release

Formatting

dotnet csharpier format .                    # whitespace + brace style (run first)
dotnet format style ArcNET.Build.slnx        # naming conventions, usings
dotnet format analyzers ArcNET.Build.slnx    # Roslyn analyzer violations

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Public API Reference

See docs/PublicApi.md for the complete public API reference.

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Credits

Reverse-engineering references that informed the binary format implementations:

• arcanum-ce — C rewrite of the Arcanum engine; primary source for object field tables (obj.c, obj_flags.h), archive format (database.h), script structures (script.h), sector layout (sector.h), and more. See references.md for the full cross-reference.
• GrognardsFromHell/OpenTemple — ToEE / Arcanum open-source engine; used for save-game format details (SaveGameInfoReader.cs, ArchiveIndexReader.cs).
• AxelStrem/ArtConverter — Reference implementation for Arcanum ART sprite format (artconverter.cpp).

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License

MIT — Copyright (c) 2026 Bia10