Deception IV: The Nightmare Princess - Recompiled

Deception IV: The Nightmare Princess (PS4) - Recompiled to PC

An (obviously) unofficial port of the PS4 version of Deception IV: The Nightmare Princess to Windows and Linux, the latest game in KOEI TECMO's unique and undeerrated trap-laying action game series.

The game's own x86-64 code runs directly on the PC: the PS4 system libraries it calls are reimplemented, and its GPU commands are drawn with Vulkan.

🚨 No game files are included 🚨

This requires you to provide a decrypted dump of your own copy of the game. Only tested with CUSA02859 with update 1.01, may work with other versions but not guaranteed.

Features

• Any window size: windowed, borderless or fullscreen, at 720p, 900p, 1080p, 1440p, 4K and more. The game renders at its native 1080p and is scaled to the window, with AMD FSR 1 RCAS sharpening.
• Update and DLC support from your own dumps.
• Built in skip intro: (optionally) fast forwards to the title menu (NEW GAME / CONTINUE) in about 6 s: the logos, the autosave notice and "Press ANY button" are sped up / skipped.
• Display settings in the game: press F10, or hold Select (View, Back, Share) for two seconds, for window mode, resolution, VSync and more.
• Keyboard and any gamepad. DualShock 4 and DualSense work as they are, Xbox-style pads by button position.
• Easy setup: point the installer at your dump, and it can add a desktop shortcut (on Linux, an application menu entry).
• Portable: saves, settings and shader caches stay in the game's folder (nothing in %APPDATA%).

Why not just use shadPS4?

shadPS4 is a general PS4 emulator, and this project builds on its video core. It is made for this one game, so it can do things a general emulator does not:

• Sound and music. The game's sound engine (KOEI TECMO's KTSL2 mixer and its streamed ATRAC9 music) is implemented in full, so sound effects and music play.
• Intro skip. A start lands on the title menu in about 6 s, past the logos, the autosave notice and "Press ANY button".
• One-step setup. Point the setup at your dump (and optionally its update and DLC): it prepares the game, adds a shortcut or menu entry, and that's it. No emulator settings or game list to manage.
• Portable. Saves, settings, logs and shader caches stay in the game's folders; nothing goes to %APPDATA%.
• In-game display settings (F10, or hold Select): window mode, window size, monitor, VSync and sharpening, changed while you play, on a page styled like the game's own menus.
• Only options that work for this game. No frame rate unlock that would speed the game up, no 4K or HDR switches it cannot use.
• Help when it breaks. A crash keeps its log and says where it is; a freeze writes what every thread was doing.

What it does not change: the game still runs at its native 30 FPS (see Frame rate) and renders at 1080p in 16:9, as it does on PS4 and on shadPS4.

Requirements

• Windows: Windows 10 or 11, 64-bit. Python and everything else comes with the release.
• Linux: x86-64 with glibc 2.39 or newer (SteamOS 3.7, Ubuntu 24.04, Debian 13, Fedora 40 or newer, Arch) and Python 3.10 or newer (python3) for the setup.
• A CPU with AVX.
• A GPU with Vulkan 1.3 and a current driver (on Linux, Mesa or the NVIDIA driver).
• A decrypted dump of your own copy of the game: the folder with eboot.bin, sce_module, sce_sys and FILE_PS4. Its update (patch) dump is optional but recommended.

Install and play

1. Download the latest release here
2. Unzip the release anywhere, for example C:\Games\Deception.
3. Run deception-setup.exe.
4. Choose your game folder (the dump), optionally an update folder (found by itself when it sits next to the game as <game>-patch, as shadPS4 keeps it) and a DLC folder, and a save folder (by default save inside the release folder). Each row says whether the folder is usable, and Install turns on once the game folder holds your dump. Press it: setup prepares the game from your dump in a few seconds and offers a desktop shortcut. Your dumps are only read, never changed.
5. Press Play Game. Later, start deception.exe or the shortcut.

Run deception-setup.exe again any time to change folders; it offers to copy your saves when the save folder moves. Untick Skip the intro there (or set skip_intro=0 in settings.ini) to see the logos and the title screen again.

The setup also works from the command line:

deception-setup.exe --game <dump> [--update <folder>|--no-update] [--dlc <folder>|--no-dlc]
                    [--save <folder>] [--skip-intro|--play-intro] [--shortcut desktop]

Works with RecompLauncher

This port works with RecompLauncher, which installs and updates it from these releases. Pick your dump on its setup screen: it prepares the game (your update is used when it sits next to the dump as <game>-patch), and the game's page shows the display, sound and intro settings. Saves go to save in the game's folder. The launcher reads recomplauncher.json, which comes with every release.

On Linux

1. Extract the release anywhere you can write: tar -xzf deception-pc-<version>-linux-x64.tar.gz -C ~/Games
2. Run deception-setup: from a file manager it asks with dialogs, in a terminal it asks there. It also takes the same arguments as on Windows (--game <dump> [--update <folder>] [--save <folder>] [--dlc <folder>]).
3. Start the game from the menu entry it adds, or run ./deception.

On a Steam Deck, do this in Desktop Mode; Add a Non-Steam Game in Steam then lists the menu entry.

Updating

Unzip the new release over the old folder and run the setup once more (the game asks you to). Your folders, saves and settings are kept.

DLC

A DLC dump is a folder per add-on, named after its label (the end of its content ID), each with its sce_sys and dlc folders. shadPS4's dlc/CUSA02859 folder works as it is:

<folder containing your DLCs>/
  DLC0000000000001/
    dlc/
    sce_sys/
  ...

Settings

settings.ini in your save folder holds every setting, each with a comment. The Display Settings panel (F10, or hold Select for two seconds) changes most of them while the game runs and saves them when it closes:

• window mode, windowed resolution (16:9 sizes, like the game; applied a second after you stop changing it) and monitor. The fullscreen modes pick their size from the screen, with black bars when the screen is not 16:9;
• VSync, and tearing with VSync off (the least input delay);
• sharpening (AMD FSR 1 RCAS, on by default), applied at once; F9 also switches it over the game, to compare.

Frame rate

The game runs at 30 FPS, as on PS4. Its logic advances one step per frame, so it cannot be unlocked: the engine has a dormant 60 FPS mode, but with it everything moves at double speed. No other cap is offered for the same reason.

Controls

The game sees one DualShock 4. Any gamepad works, mapped by button position: on an Xbox pad A B X Y are Cross, Circle, Square, Triangle, LB/RB are L1/R1, LT/RT are L2/R2, Menu is Options and View clicks the touchpad. The keyboard works alongside a gamepad:

Keys	PS4
W A S D / I J K L	left stick / right stick
arrow keys	d-pad
Space, Enter	Cross
Escape, Backspace, ;	Circle
F / H	Square / Triangle
Q, Page Up / O, Page Down	L1 / R1
E / U	L2 / R2
X / M	L3 / R3
Tab, P	Options
T	touchpad click

Shortcut	What it does
F10, or hold Select 2 s	Display Settings
F9	sharpening on or off
F4	asks "Exit Deception?" (No is selected first)
Alt+F4	closes the game without confirmation

When something goes wrong

The game logs to deception.log in the log folder of your save folder. If it closes by itself, it says so and keeps that log as crash-<date>-<time>.log in the same folder; attach that file when you report the problem. If the picture freezes, leave the game running for half a minute before closing it: after 20 seconds without a new frame it writes what every thread is doing to the log.

Building from source

docs/building.md covers the toolchain, building, tests and packaging, and docs/development.md how the runner works and how to work on it.

🤖 AI usage disclaimer 🤖

This project was thoroughly made by AI.

I (human) am a programmer, but I know nothing about C++ which is required to make this possible. And so, I've done precisely three things in this project:

1. Paid for AI
2. Told AI what to do
3. Tested out whatever AI did

Credits and license

Based on and inspired by theatrhythm-fbl-pc.

GPL-2.0-or-later, see LICENSE. The overlay uses the fonts DejaVu Sans (Bitstream Vera license), Cinzel and Josefin Slab (SIL Open Font License 1.1); their licenses are in gpu/third_party/fonts. Runtime follows shadPS4. Deception IV: The Nightmare Princess is a game by KOEI TECMO GAMES; this project is not affiliated with or endorsed by them.