PocketMonstersStadiumRecomp

⚠️ This project is very early and expected to be buggy. It was forked from the US Pokémon Stadium recompilation to see how far the same approach could get on the original Japanese Pocket Monsters Stadium. Pokémon Stadium had solid pret decompilation coverage to lean on; this game does not, which has made tracking down bugs slow and difficult — so development will likely be set down until someone takes the time to properly decompile and annotate the ROM. The game also never had an official translation, so an in-memory English text layer has been adapted for most scenes; it is not exhaustive and has its own formatting and layout glitches. Treat everything here as a work in progress that is likely to break.

An experimental Windows build is under Releases (v0.0.2). No ROM is bundled — bring your own Pocket Monsters Stadium (J) .z64.

Static recompilation of Pocket Monsters Stadium (Japan) — the original Japanese release that predates the international Pokémon Stadium — to a native PC program.

This turns the original game into a native PC executable instead of running it in an emulator. Most of the work is teaching the recompilation toolchain about this one specific ROM. It is a sibling of PokemonStadiumRecomp (the US Pokémon Stadium recomp) and uses the same companion repositories:

• N64Recomp — the static recompiler
• N64ModernRuntime — the runtime that stands in for the N64's operating system
• rt64 — the graphics renderer

All three track the main branch; the exact commit this tree builds and boots against is recorded in n64recomp.pin.

Why a separate repo from PokemonStadiumRecomp? PMS-J is the same engine family as US Pokémon Stadium (near-identical boot layout — Idle_ThreadEntry at the same address 0x80000460), which makes PSR's pret-decompiled source an excellent oracle for identifying unnamed PMS functions. But the ROM, symbol map, and game logic differ, so it gets its own recompilation tree.

Status

Boots to the interactive main menu. From a cold start the recomp runs the full resident init (cooperative scheduler, libleo no-drive resolution, audio engine, resource server), builds graphics tasks, and renders the iconic terminal / Poké Ball main-menu scene — including the Japanese "no cartridge inserted" prompt and the オプション (Options) button.

It now boots through the title (the PRESS START / njpeg background renders), the cart-select screen, the main menu, and into the 3D battle UI, with the runtime English-translation layer applied. The bring-up trail — the boot deadlock (scheduler starvation on loop back-edges), truncated delay-slot corruption, the libultra identifications, and the resource-server layer — is documented in FINDINGS.md.

Very experimental — expect bugs. Known issues (in progress):

• GB mode / GB Tower does not work — it currently mis-flags valid Game Boy save data as "corrupt" and won't load imported Pokémon.
• Pokémon registration appears to work (importing your party into Stadium); it is GB Tower play that does not.
• Pokémon Green (Japanese, unmodified) is the only tested cartridge — and even it currently does not show a proper icon when loaded. Other-language, modified, and other Game Boy cartridges are untested and may not work.
• The English translation is incomplete — many strings are still Japanese, and some translated text may be wrong or mis-sized.
• Some UI sprites (arrow/hand) still have transparency artifacts, and deeper play paths can hit crashes/hangs.

English translation patch

PMS-J ships only in Japanese. This project includes an optional runtime English-translation layer that replaces the game's on-screen Japanese with English as it is drawn — no ROM modification, no asset re-packing. The main menu, battle/tournament setup, cup and rule descriptions, rental Pokémon, moves, types and stat screens are translated (269 strings and growing).

How it works (short version): the recompiled game funnels almost all of its text through one string-draw routine. A hook reads the source bytes at that routine, hashes them, looks the hash up in a small JSON table (translations.json), and on a hit re-renders the English replacement through the game's own font glyphs (the font already contains Latin letters, so no glyph injection is needed). Untranslated text falls through unchanged, and the table hot-reloads while the game runs. Replacement text is not bounded by the original length, and Latin spacing is tightened so English fits the Japanese text boxes.

The hook is built on the always-on diagnostic-ring + per-function trace infrastructure in the runtime fork. For the full design and internals, see the N64ModernRuntime fork — the runtime that exposes the guest-memory access and trace surface this is built on.

Using / extending it:

# Translations live next to the executable as translations.json (the repo
# root copy is the canonical data). Regenerate it from the source table any
# time — it hot-reloads, no rebuild needed:
python tools/pms_build_translations.py build      # tools/key_en.tsv -> build/translations.json

# Capture the strings on screens you visit (always-on; survives crashes),
# then list what still needs translating and add lines to tools/key_en.tsv:
python tools/pms_build_translations.py decode     # accumulate -> tools/strings_decoded.tsv
python tools/pms_build_translations.py todo       # -> tools/untranslated.tsv (key <TAB> Japanese)

Run with PMS_TEXTPROBE=1 to arm string capture (and the textdump / stringdump / fontdump debug-server commands). PMS_XLATE_GAP tunes the letter spacing. The capture/translate tooling lives in tools/.

ROM

Field	Value
Title	Pocket Monsters Stadium (Japan)
MD5	c46e087d966a35095df96799b0b4ffae
Size	16,777,216 bytes (16 MB)
Format	.z64 (big-endian native, magic 80 37 12 40)

The ROM is commonly distributed byte-swapped as .v64; convert it to native big-endian .z64 before use. The original game's data is not included — a legal copy of your own dump is required to build or run this project. Place it at the repo root as baserom.z64 (gitignored).

Layout

├── baserom.z64           # canonical PMS-J ROM (gitignored — bring your own)
├── lib/                  # engine forks, junctioned by setup (gitignored)
│   ├── N64ModernRuntime/ # runtime (embeds N64Recomp submodule)
│   └── rt64/             # graphics renderer
├── ghidra/               # Ghidra seed project (live .rep gitignored)
├── generated/            # recompiler C output (gitignored — regen via N64Recomp)
├── rsp/                  # RSP microcode reimplementations (aspMain, njpgdsp)
├── src/main/             # app entry, render context, debug server, diagnostics
├── include/              # app headers
├── tools/                # game-specific tooling (libultra matcher, symbol gen,
│                         #   Ghidra seed/export, delay-slot fixer, fuzz driver)
├── game.toml             # N64Recomp config (patches + build decisions)
├── symbols.toml          # symbol map
├── functions.json        # function-entry list (symbols-file build mode)
├── function_*.txt        # add/drop/merge/rename/size overrides
├── aspMain.j.1.0.toml     # RSP audio microcode descriptor
├── aspmain_combined.bin   # combined audio microcode blob
├── n64recomp.pin         # companion-fork SHA pins
├── CMakeLists.txt        # build entrypoint
├── setup.sh / setup.bat  # provisioning (junctions lib/, inits submodule)
├── FINDINGS.md           # reverse-engineering log
└── README.md

Quick start

# 1. Provision the engine forks under lib/ (junctions the sister checkouts
#    ../N64ModernRuntime and ../rt64 if present, else clones them).
./setup.sh           # Windows: setup.bat

# 2. Drop your verified PMS-J ROM at the repo root as baserom.z64.

# 3. Configure + build.
cmake -S . -B build -G Ninja -DCMAKE_BUILD_TYPE=Release
cmake --build build

# 4. Run (auto-selects baserom.z64 from the working directory).
./build/PocketMonstersStadiumRecomp        # Windows: build\PocketMonstersStadiumRecomp.exe

Useful environment knobs: PMS_VOLUME (master volume 0–1), PMS_DEBUG_PORT (enable the scripted debug server), PMS_BOOT_WATCHDOG=1 (post-mortem ultra-trace dump on stall/abort).

Acknowledgements

• pret/pokestadium — the US Pokémon Stadium disassembly that serves as the engine oracle for PMS-J.
• the ares emulator team — accuracy reference.

License

PocketMonstersStadiumRecomp is distributed under the GNU General Public License, version 3 — see COPYING.

It is built from several components under their own licenses, whose terms and copyright notices are retained in their respective repositories:

• N64ModernRuntime — GPL-3.0 (COPYING)
• N64Recomp — MIT (LICENSE)
• rt64 — MIT (LICENSE)

The original game's assets are not included; a legal copy of the Pocket Monsters Stadium (J) ROM is required to build or run this project.

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