Fable: The Lost Chapters — Decompilation & Native Modding

An evidence-gated reconstruction of the native 32-bit Windows Fable.exe, targeting readable, buildable C/C++ source and a durable native modding platform.

Actively developed — October 24, 2026. Native C/C++ reconstruction is continuing. Recent local tests render a retail title sprite through recovered drawing routines and validate connected texture-loading and lifetime paths. The existing interactive frontend is an authored integration checkpoint, not proof that the reconstructed native engine boots or that the game is playable. Latest native progress and remaining boundaries.

Run the checkpoint · See current progress · Read the roadmap · Browse the documentation · Project layout and workspace care

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Contents

1. Project
2. Current progress
3. Run the checkpoint
4. What works today
5. Roadmap
6. Verification pipeline
7. Documentation
8. Repository layout
9. Project boundaries
10. Why this is tractable

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1. Project

The goal is a full decompilation of Fable: The Lost Chapters for PC: a complete source reconstruction that can be understood, built, tested, and extended.

This is not a source port or a static recompilation of another architecture. TLC already ships as a clean native x86-32 PE built with Microsoft Visual C++ 7.1. The project combines static analysis, donor-symbol recovery, live instrumentation, original-compiler reconstruction, and retail-byte comparison.

The work has three connected outputs:

• Decompilation: faithful VC7.1-compatible source, one verified function at a time.
• Runnable reconstruction: recovered startup, frontend, rendering, media, and eventually gameplay systems connected into executables.
• Native tooling: reusable format, scripting, editor, viewer, and modding knowledge produced by the reverse engineering.

Where to look first: ROADMAP.md is the single task list (done / in flight / next), HANDOFF.md is the one-page resume point, ARCHITECTURE.md explains the source layers, BUILDING.md the toolchain, and CONTRIBUTING.md the landing rules. The full strategy is in FULL_DECOMP.md; every other document is listed in docs/INDEX.md.

On readability. Early landed code modelled this with throwaway local structs (struct T { char pad[0x1a8]; ... }). Since 2026-09-07 the class layouts recovered from the debug PDB are emitted as compilable, PDB-named headers in rebuild/include/engine/, and landed functions are retyped onto them only when the rewritten file still compiles to the identical retail bytes. The "Readability" rows in the metrics below track that conversion; the remaining generic declarations are a worklist, not the intended end state.

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2. Current progress

Latest activity: October 10, 2026. See the native development update for recent recovery and real-GPU validation. This publication updates project status; the newer local source/test checkpoint is not yet merged into main. The generated whole-project figures below remain the September 7 snapshot, not current completion estimates. Native subsystem checkpoint counts must not be added to these totals without a reconciled dashboard refresh.

Snapshot	Current result
Catalogued retail functions	49,568
Verified functional or matching reconstruction	18,579 · 37.48%
Byte-identical reconstruction	8,082 · 16.30%
Accepted analysis naming quality	99.211%
Runnable milestone	Authored integration checkpoint: boot movies + interactive frontend, Saved Games, and Options screens

Snapshot functional-or-matching coverage is 37.48% of the 49,568-function catalog. Of that verified set, 16.30% is byte-identical C++. The first 5% byte-match milestone has been passed.

<details> <summary><strong>Full generated metrics</strong></summary>

The canonical refresh updates this table from the checked compile, behavior, parity, coverage, and naming reports:

Track	Metric	Status
Analysis DB	Functions catalogued	49,568
Analysis DB	Mechanically named (no FUN_*)	100.000%
Analysis DB	Accepted naming quality	99.211%
Analysis DB	Usable reconstruction/navigation names	99.913%
Analysis DB	Calling convention known	77.746%
Analysis DB	Complete non-undefined prototype	69.174%
Reconstruction	Curated sources, VC7.1-compiled and behaviour-gated	18,604
Reconstruction	Verified functional or matching C++	18,579 (37.48%)
Reconstruction	— of which byte-identical C++	8,082 (16.30%)
Reconstruction	— of which hand-written asm bakes (grade asm_bake, not counted as reconstruction)	292
Readability	Landed sources typed onto shared PDB-named engine headers	651
Readability	Throwaway local struct T {...} declarations remaining	4,417
Reconstruction	Compiled sources still honestly DIFFER	43
Reconstruction	Compiled rows lacking a Ghidra function-start oracle	0
Auto-RE intake	Generated candidates / structural checker PASS	1,066 / 1,053
Boot path	GFMain direct-call sites proven	257 / 257 (100.00%)
Boot path	Callable authored GFMain phases	10 / 10 (100.00%)
Boot path	Current Phase 10 direct calls proven	21 / 21 (100.00%)
Modern C++23	GFMain phases promoted into the modern startup lane	0 / 10 (0.00%)

Counts above are from the 2026-09-07 canonical refresh: rebuild/manifest/status.json, rebuild/compile-gate/retail-parity.json, rebuild/COVERAGE.md, and the naming-quality reports.

Generated agent output is tracked separately and is never counted merely because a structural checker accepted it. The 37.48% figure is intentionally the strict, whole-executable denominator. Boot-path figures are a separate view of the 3,952-byte GFMain coordinator, not an estimate of total engineering time. The C++23 startup figure is deliberately separate too: exact x86 parity and readable integration work do not count as a modern port merely because their interfaces are becoming stable.

</details>

The public dashboard is refreshed only after the compile/parity pipeline has settled. Unreviewed background-agent output does not silently change these numbers.

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3. Run the checkpoint

This runs the authored frontend/integration checkpoint already published in main. It is not a playable native-engine reconstruction or the newer local retail-title raster test described in the October update.

From the repository root:

powershell -ExecutionPolicy Bypass -File rebuild/build_bootstrap.ps1

Then launch the retail-layout checkpoint with the optional BuffJesus text variant:

.\rebuild\build\bootstrap-Release\FableTLC-Reconstruction-VisualCheckpoint.exe --buff-jesus

Useful switches:

Switch	Behavior
--buff-jesus	Changes main-menu strings while preserving retail geometry, actions, videos, and assets.
--skip-boot-videos	Fast developer launch directly into the frontend.
--retail-video	Exercises the recovered retail movie path.
--retail-video-upscaled	Uses an explicitly generated local 2× video cache when available.

The normal BuffJesus path includes Lionhead, Microsoft, and intro_comp movies. Escape skips the current movie. Retail banks are read from the local game installation at build/runtime; they are not committed to this repository.

For smoke commands, prerequisites, individual movie modes, and the honest runtime boundary, see rebuild/RUNNABLE.md.

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4. What works today

Area	Verified state	Major remaining boundary
Analysis database	Nearly complete navigation-quality names with recovered prototypes and calling conventions	Resolve the remaining ambiguous types, function starts, and hard naming stragglers
Function reconstruction	See the generated metrics above (byte-identical genuine C++, functional-or-matching, asm bakes reported separately)	Continue strict promotion; retype landed code onto the shared PDB-named headers; de-bake the asm_bake grade
Startup	Retail-matched WinMain, all ten authored GFMain phases callable, connected exact GFInitialise, progress-display ownership	Replace the remaining GFMain dependency boundaries and pursue whole-coordinator retail parity
Frontend	Boot movies, retail-data-driven interactive menus, CUIState-driven main-menu/Save/Options rows, keyboard/mouse/controller navigation, Credits routing, profile/delete/new-profile branches, Continue-to-Saved-Games routing, and retail list/transition sounds	Visual sign-off is still open: compare identical retail/reconstruction captures; link native profile persistence and validated save action 0x11 only at their recovered manager/game boundaries
Controls	Interactive capture/cancel/apply, duplicate clearing, W/S/A/D movement expansion, arrow/WASD reset actions, and recovered wheel/arrow ingress for authored scrolling lists	Full 31-action Redefine materialization/filtering/coexistence, profile persistence, and remaining controller/action ownership
Video	Retail movie order, end-of-stream advancement, Escape skip, and D3D9 texture publication	Replace the compatibility presentation seam with reconstructed CTexture/CMovie::Draw submission
Particles and lighting	Asset reports, billboard/crossed-sprite contracts, blend state, shader assembly, environment/RSA lookup, sky inputs	Recover constant semantics, signed/special passes, shadows, and golden viewer captures
Modding research	Broad readers/writers for definitions, levels, terrain, meshes, animation, audio, text, quests, and saves	Consolidate them behind safe product workflows and runtime validation
Cut multiplayer	Player slots, event/package codecs, local initialization, and a grounded revival plan are documented	Reconstruct synchronization, seating, lifecycle, and transport before enabling anything

This table is a landing-page summary. Detailed addresses, byte counts, evidence, and caveats live in the subsystem documents (docs/engine/, docs/formats/, docs/pipeline/); the chronological record is docs/journal/.

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5. Roadmap

The roadmap is a checklist, not prose: docs/ROADMAP.md. It has one "current focus" block and seven lanes (repo health, symbols and types, byte-parity reconstruction, runnable frontend, engine subsystem RE, quest-script recovery, modding toolchain), each with [x] done / [ ] open items that point at their owning document. Superseded plans are archived under docs/journal/.

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6. Verification pipeline

Every promoted function passes an evidence chain:

1. Recover — Ghidra, donor PDB/BSim evidence, runtime traces, and retail bytes establish identity, boundaries, ABI, and behavior.
2. Author — readable C++03/VC7.1-compatible source is placed in the address-sharded reconstruction tree.
3. Test — the original VC7.1 compiler builds the function and a focused behavior fixture exercises its contract.
4. Compare — object .text is compared with authoritative retail bytes, with only real COFF relocation fields normalized.
5. Land — only reviewed MATCH, RELOCATION_MATCH, or explicitly behavior-only results enter their corresponding honest totals.

The result is intentionally conservative:

• MATCH means byte-identical.
• RELOCATION_MATCH means identical after expected relocation normalization.
• DIFFER remains visible even when behavior passes.
• ORACLE_MISSING is never guessed into parity.
• Generated/structural PASS is intake, not reconstruction credit.

Implementation details:

• decomp pipeline
• source architecture
• parity triage
• methodology
• toolchain setup

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7. Documentation

Inspired by documentation-first projects, this README is the index; deep technical material lives in focused documents.

Start here

Document	Purpose
NATIVE_STATUS.md	Latest native development update and publication boundaries
HANDOFF.md	Current public handoff and historical resume state
ACTIVE_TASK_LIST.md	Ranked work with acceptance gates
rebuild/RUNNABLE.md	Build, launch, smoke, and runtime-boundary instructions
TOOLCHAIN.md	Ghidra, BSim, FSE, VC7.1, and local prerequisites
CAPABILITY_INDEX.md	Index of recovered tooling and format capabilities

Reconstruction

Document	Purpose
FULL_DECOMP.md	Full-decomp strategy and promotion model
TECHNICAL_BRIEF.md	Current architecture, evidence grades, boot status, and modernization boundaries
SOURCE_ARCHITECTURE.md	Generated, parity, and modern-source boundaries
BSIM_PORT.md	Donor-symbol porting runbook
DECOMP_ACCELERATORS.md	Automation and throughput options
UNICORN_EMULATION_PLAN.md	Optional bounded x86 behavior-oracle pilot

Runtime, UI, and rendering

Document	Purpose
FRONTEND_FORMAT.md	Recovered frontend definitions, tables, actions, and transforms
VIDEO_SYSTEM_RE.md	CVideoSys/CMovie, DirectShow, and texture-presentation recovery
PARTICLE_LIGHTING_VIEWER_HANDOFF.md	Particles, billboards, RSA/environment lighting, shaders, sky, and shadows
UI_UPSCALE_PLAN.md	Optional high-resolution cache policy and validation
COOP_REVIVAL.md	Evidence and safe order for the cut multiplayer system

Content and modding

Document	Purpose
COMPREHENSIVE_MODDING_ENVIRONMENT.md	Overall tool/editor environment
CONTENT_AUTHORING_PLAN.md	Safe content-creation workflow
SYSTEMS_ANALYSIS.md	Per-subsystem maps and moddability verdicts
FINDINGS.md	Cross-checked technical findings
FABLE_TLC_REPORTED_BUGS.md	Evidence template for reported game defects

The docs/ directory contains focused references for definitions, BIG archives, textures, meshes, animation, audio, terrain, navigation, quests, scripts, saves, and editor integration.

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8. Repository layout

Path	Contents
rebuild/	Buildable reconstruction, tests, manifests, oracles, integration, and parity reports
lift/	Auto-RE candidate reports, configuration, and durable worker state
ghidra_out/	Reproducible labels, APIs, decompilation exports, and naming audits
tools/	Ghidra scripts, promotion pipeline, reports, asset/format tools, and smokes
docs/	Technical references, plans, runbooks, and handoffs
refs/	FSE and other compact reference manifests
work/, snapshots/, dist/	Ignored local experiments, generated artifacts, and share packages

See WORKSPACE_LAYOUT.md for ownership and cleanup rules.

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9. Project boundaries

• No retail executable, artwork, video, archive, PDB, or decoded asset is committed.
• Retail-derived screenshots, texture decodes, model renders, Blender files, and byte-oracle extracts are local-only test outputs and are ignored by Git. Tests must generate them from a user-supplied installation outside the repository.
• A local retail installation is used as read-only evidence and asset input.
• Generated agent code is never treated as verified merely because it exists.
• A visually similar checkpoint is not claimed as the complete retail renderer.
• A behavior-equivalent function is not claimed as byte-identical.
• Experimental dependencies such as Unicorn remain optional and isolated from canonical builds until their licensing and technical boundaries are proven.
• Any tool capable of modifying game data must use explicit staging, validation, backup, and rollback paths.

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10. Why this is tractable

• Fable.exe is a clean MSVC PE32 image without a packer or DRM wrapper.
• FableScriptExtender contributes a large native scripting/API map.
• PDB-bearing Lionhead binaries provide rich donor names and type lineage.
• BSim and reproducible overrides transfer that evidence into retail.
• The original VC7.1 compiler is available for instruction-level comparison.
• Two decades of community research cover many data formats while this project concentrates on engine internals and faithful reconstruction.
• Every promotion is measurable, reviewable, and reversible.

The destination is ambitious, but the next step is always concrete: identify a boundary, recover a contract, compile it with the original toolchain, test it, compare it with retail, and only then count it.

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