# ReC98: the Touhou PC-98 Restoration Project

> Reconstructs C++ and assembly source for the first five Touhou games, released by ZUN for the NEC PC-9801 in 1997–1998, under a rule that no master commit may change the decompressed program image or relocations of any original executable as compared by the project’s mzdiff tool. TH01 was fully decompiled in August 2022; code not yet decompiled stays in the tree as IDA-generated disassembly, and the project’s blog documents what each part of ZUN’s code does. Separate debloated and anniversary branches restructure the code and fix bugs as bases for ports and mods.

- Type: Case study
- Targets: Game
- Category: Independent reconstruction cases
- Relationship: Independent reconstruction project
- Sources reviewed: 2026-10-19
- Added to the catalog: 2026-11-09
- Original resource: <https://github.com/nmlgc/ReC98>
- Primary source: <https://github.com/nmlgc/ReC98/blob/b6ba5b0a529edbb31efdf8c0e939263804f8ee47/README.md>
- Catalog page: <https://awesomerea.org/resources/rec98-touhou-pc98-restoration-case/>
- Record JSON: <https://awesomerea.org/resources/rec98-touhou-pc98-restoration-case/record.json>
- Chinese version: [简体中文](https://awesomerea.org/zh/resources/rec98-touhou-pc98-restoration-case/index.md)

## Requirements & limits

- The project targets the first five Touhou PC-98 games. TH01 was fully decompiled in August 2022; other games remain in progress. Master permits only instruction-encoding differences and trailing zero padding under mzdiff; ports use the debloated branch and bug fixes use anniversary or single-fix branches.
- Running the built PC-98 executables requires each game’s original files beside the output. The repository omits original asset data. Builds require Borland Turbo C++ 4.0J and Borland Turbo Assembler 5.0 or later (TASM32.EXE); neither is bundled.
- Windows 11 x64 and Windows XP 32-bit are tier-1 build platforms; Wine on 64-bit x86 Unix is tier 2. The output runs in DOSBox-X or the project’s Neko Project II debug fork.
- The root has no license file. Bundled MS-DOS Player and Tup builds are GPLv2; master.lib, the Pi loader, SPRITE16 and KAJA PMD files are third-party components. Rights to the original games remain with their owner.

## Primary sources

1. <https://github.com/nmlgc/ReC98/blob/b6ba5b0a529edbb31efdf8c0e939263804f8ee47/README.md>
2. <https://github.com/nmlgc/ReC98/blob/b6ba5b0a529edbb31efdf8c0e939263804f8ee47/CONTRIBUTING.md>
3. <https://github.com/nmlgc/ReC98/blob/b6ba5b0a529edbb31efdf8c0e939263804f8ee47/bin/README.md>
4. <https://github.com/nmlgc/ReC98/blob/b6ba5b0a529edbb31efdf8c0e939263804f8ee47/build.bat>
5. <https://github.com/nmlgc/ReC98/blob/b6ba5b0a529edbb31efdf8c0e939263804f8ee47/Tupfile.lua>
6. <https://github.com/nmlgc/ReC98/tree/28d59d31331e27fcbe61d1b65bd8c0cd618757d8>
7. <https://github.com/nmlgc/ReC98/tree/c7019963ac643333114ccba9ef10adb3728f2384>
8. <https://rec98.nmlgc.net/>

## More in Games

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- [Resident Evil: Code: Veronica — matching Dreamcast decompilation](https://awesomerea.org/resources/recv-dc-decomp/index.md) · Case study
- [Rhythm Tengoku Arcade: SH-4 decompilation and asset-format reconstruction](https://awesomerea.org/resources/rhythm-tengoku-arcade-decomp-case/index.md) · Case study
- [Ridge Racer (PSP): bit-exact decompilation of BOOT.BIN](https://awesomerea.org/resources/ridge-racer-psp-decomp-case/index.md) · Case study
- [River Raid: an annotated ZX Spectrum disassembly](https://awesomerea.org/resources/river-raid-zx-disassembly-case/index.md) · Case study
- [Rock Band 3: agent-assisted Xbox 360 matching decompilation](https://awesomerea.org/resources/freeqaz-rock-band-3-xenon-case/index.md) · Case study

## About this entry

The description was reviewed against primary sources.
Original editorial content: MIT. Linked projects, papers and assets retain their own rights and licenses.