Shin Megami Tensei IV for PC (smt4-recomp)

Shin Megami Tensei IV for PC (smt4-recomp)

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A native Windows build of Shin Megami Tensei IV (3DS, USA), made by static recompilation: 3dsrecomp translates the game's ARM code into C ahead of time, and that C is compiled into a program of its own, with Zakuro as the runtime for everything else (kernel, services, GPU, sound). The game's code runs natively, not through an emulator's interpreter or JIT.

On top of that, this project adds widescreen, multipliers for Macca, EXP and App Points, frame rate options and cheats, all switched from the in-game cheat menu.

Beta. Played from a new game for more than 10 hours with no crash. The rest of the game hasn't been played on it yet: please report what you find in Issues.

No game files or game code are included, and there is no download. You build it yourself from your own dump of the game. What the build makes (code/ and the program) holds the game's code: don't share it. This project is not affiliated with Atlus, SEGA or Nintendo.

Contents

• Features
• Requirements
• Building
• Playing
• Cheats and enhancements
• Controls
• Extracting assets
• Troubleshooting
• How it works
• Credits
• License

Features

• Native code: the game's ARM code recompiled to C and compiled for the PC (95% of it found ahead of time; anything left runs in Zakuro's interpreter).
• Widescreen 16:9 and 21:9: the game draws a wider 3D scene (more view at the sides, same height), not a stretched picture.
• Multipliers x2, x3 and x5 for Macca, hero EXP, demon EXP and App Points, each picked from the cheat menu while playing.
• Easy Recruit: demon negotiations always go your way, from the cheat menu.
• 60 FPS (the game runs twice as fast with it) and 30 FPS to go back.
• Community cheats: max Macca, App Points, items, hero EXP, HP/MP and stats.
• Everything Zakuro has: Vulkan or OpenGL, screen layouts, scaling and filters, save states, controllers, 3D.

Requirements

• Windows 10 or 11, 64-bit. Linux should work too, but hasn't been tried.
• A graphics card with Vulkan (or OpenGL 3.3).
• Your own decrypted dump of Shin Megami Tensei IV (USA), title ID 00040000000E5C00, as .3ds or .cci.
• About 10 GB of free disk space and 8 GB of RAM for the build.
• To build:
  • Rust with the GNU toolchain: rustup default stable-x86_64-pc-windows-gnu
  • MinGW-w64 GCC, 64-bit: winget install BrechtSanders.WinLibs.POSIX.UCRT
  • git

Building

With the launcher

launcher/ is a small program that does it all from a window: choose the folder with your game (it finds the ROM in it), see which tools are missing and install them with winget, download or update this project, build the game with a progress bar, and play.

cd launcher
cargo build --release
target\release\smt4-launcher.exe

It holds no game code, so it can be shared.

From the command line

git clone https://github.com/Invictus-potens/smt4-recomp
cd smt4-recomp
cargo build-game "C:\path\to\Shin Megami Tensei IV (USA).3ds"

cargo build-game (the builder in tools/build) checks your tools and ROM, fetches and builds 3dsrecomp at the version this project was tested with, recompiles the game's code with this project's changes, builds the program and copies the cheats to Zakuro's cheats folder (adding the missing ones to a cheats file already there, without touching the rest). The recompilation takes 20 minutes or more; add --low-priority to keep using the PC meanwhile. Running it again later only redoes what changed. cargo build-game --help lists the options.

When it's done, the program is target\release\smt4.exe.

Playing

target\release\smt4.exe "C:\path\to\Shin Megami Tensei IV (USA).3ds"

It reads the game's files and everything but the code from your dump, so keep the ROM where it is. Saves, save states and settings go in Zakuro's folder, %APPDATA%\zakuro.

Recommended setup (Escape opens the menu):

1. Settings, Layout: Top screen only. F10 switches to the bottom screen and back, for the map and menus.
2. Settings, Top screen shape: 16:9 (or 21:9 on an ultrawide).
3. Cheats: turn on Widescreen 16:9 (the same shape), then go to another area so the game sets its camera again.

Cheats and enhancements

Escape, then Cheats. The ones marked smt4-recomp only work in this build; Enhancements are built into Zakuro, at the top of the window; the others are standard Action Replay codes.

Cheat	What it does
Widescreen 16:9 / 21:9 (smt4-recomp)	Wider 3D scene. Needs Top screen shape set to the same, and shows at the next area change.
Macca x2 / x3 / x5 (smt4-recomp)	Multiplies Macca from battles, shops and rewards. Shops show the normal price; the money you get is multiplied.
Hero EXP x2 / x3 / x5 (smt4-recomp)	Multiplies the hero's EXP from battles.
Demon EXP x2 / x3 / x5 (smt4-recomp)	Multiplies the EXP demons get (party and stock).
App Points x2 / x3 / x5 (smt4-recomp)	Multiplies App Points.
Easy Recruit (smt4-recomp)	Every negotiation goes your way: answers work, refusing or not having what it asks still works, and the demon doesn't run off or cheat you. It still asks for things.
60 FPS (Enhancements)	The game logic is tied to the frame rate, so everything runs twice as fast. Turning it off does not bring the normal speed back: use 30 FPS for that.
30 FPS (Enhancements)	The game's default; undoes 60 FPS.
Max Macca, 9999 App points, All items, Hero Max Exp, Hero HP/MP, Hero Stats	Community codes.

Turn on only one of each multiplier. Turning a multiplier or widescreen cheat off goes back to normal on its own.

How they work: MULTIPLIERS.md, WIDESCREEN.md, RECRUIT.md.

Controls

Keyboard defaults, all changeable in Settings. Controllers work too.

3DS	Key		Zakuro	Key
A / B	X / Z		Menu	Escape
X / Y	S / A		Pause	F1
L / R	Q / W		Save / load state	F5 / F8
ZL / ZR	1 / 2		Next layout	F9
Start / Select	Enter / Backspace		Top / bottom screen	F10
D-pad	Arrow keys		Full screen	F11
Circle Pad	I J K L		Fast forward	hold Tab
C-Stick	T F G H		Touch screen	mouse

Extracting assets

tools/extract pulls the game's files out of your ROM and converts them: textures to PNG, models to plain CGFX (for SPICA, Ohana3DS or Noesis), text to UTF-8, music, sounds and voices to WAV, cutscenes to MP4.

cd tools\extract
cargo build --release
target\release\smt4-extract "C:\path\to\Shin Megami Tensei IV (USA).3ds" C:\smt4-assets

The formats, what's converted and what isn't: ASSETS.md. Like the build, what it writes is the game's: don't share it.

To replace an image of the game with your own (a portrait, an icon, a background), at the same resolution or higher:

cargo fit-texture <assets>\textures\tex\stex\stbustup\st_bu_pc001.png my_picture.png

It fits your picture where the original's character is and installs it as a texture pack; restart the game to see it. Step by step, and what to do when an image doesn't change: MODDING.md.

Troubleshooting

• "no 64-bit gcc found": only an old 32-bit MinGW is installed (one that comes first on PATH is skipped on its own). Install MinGW-w64, for example winget install BrechtSanders.WinLibs.POSIX.UCRT, or set CC and AR to the full paths of a 64-bit gcc.exe and ar.exe.
• .drectve ... unrecognized warnings, then a link error: the gcc that comes with Strawberry Perl has a linker too old for current Rust. The build skips it on its own when another 64-bit gcc is installed; install one with winget install BrechtSanders.WinLibs.POSIX.UCRT.
• "Rust uses the MSVC toolchain", or errors about link.exe: run rustup default stable-x86_64-pc-windows-gnu.
• "is title ..., this project is for Shin Megami Tensei IV (USA)": only the USA release is supported; the code differs between regions.
• The game runs twice as fast: 60 FPS was on at some point. Turn on 30 FPS (Enhancements), then save a state again.
• The picture is squeezed or stretched: the Widescreen cheat and the Top screen shape setting have to match, or both be off.

How it works

Part	Where	What it does
Launcher	launcher/	A window around tools/build: finds the ROM, checks the tools, builds, plays
Builder	tools/build (cargo build-game)	Runs every step below, from your ROM to the program
Recompiler	3dsrecomp	Finds the game's functions and writes them as C, into code/ (not in this repo)
Overrides	overrides/	Functions written by hand that replace generated ones: the Macca and App Points multipliers, widescreen
Patches	tools/build/src/patch.rs	Changes the generated C where an override can't reach (hero and demon EXP, the projection)
Program	Cargo.toml, build.rs, src/main.rs	Links the compiled code with Zakuro
Runtime	Zakuro	3DS kernel, services, GPU and sound
Image mods	tools/fit-texture (cargo fit-texture)	Makes and installs a texture pack picture, see MODDING.md
Asset extractor	tools/extract/	Pulls the game's files out of the ROM and converts them, see ASSETS.md
Cheats	cheats/00040000000E5C00.txt	Codes for Zakuro's cheat menu; the smt4-recomp ones write a control byte the overrides read

This is static recompilation, not a decompilation: there is no readable source code of the game here or anywhere in the build. Set SMT4_HOOK_LOG to a file path to have every multiplied gain written to it.

More: progress and known issues, enhancements and roadmap.

Credits

• fearkov: 3dsrecomp and Zakuro, which do the heavy lifting.
• lucky: the 60 FPS and 30 FPS codes, from Reshiban/60FPS-AR-CHEATS-3DS.
• JourneyOver and the codes' original authors: the community cheats, from JourneyOver/CTRPF-AR-CHEAT-CODES.
• Shin Megami Tensei IV is by Atlus.

License

MIT, for the files in this repository only. It doesn't cover the game or anything built from it.