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 (SaveGame, SaveGameLoader, SaveGameWriter) and 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 (SaveGameLoader), inspect and mutate parsed mobiles / sectors / scripts, write back (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