UnityPlayerPatcher

<h1 align="center">⚠️ This method is deprecated ⚠️</h1> <p align="center">➡️ See updated <code>How to use</code> below ⬅️</p>

UnityPlayerPatcher

A low-level binary patcher designed to modify the Unity engine portable executable (PE) binary called UnityPlayer.dll for the game PEAK, specifically targeting and disabling the handling of the -force-vulkan command-line argument. This is achieved through direct assembly-level modifications, effectively preventing the engine from initializing with the Vulkan graphics backend, regardless of launch parameters.

<details> <Summary>Motivation</Summary> PEAK's current Steam launch configuration includes `force-vulkan` as its default launch option. As a result, launching the game directly (outside of Steam) will always apply the `force-vulkan` parameter. This forced Vulkan mode can cause compatibility issues, including preventing certain mods from working entirely. UnityPlayerPatcher addresses this issue by bypassing the forced Vulkan activation, allowing users to run the game and their mods without restriction. </details>

How to Use

This patcher is now integrated in my fork of Unity Doorstop that is included in the BepInExPack for PEAK. This allows me to patch UnityPlayer at runtime, giving you an untouched UnityPlayer.dll when the game closes.

New way to bypass Vulkan

Make sure you have the latest version of BepInExPack for PEAK (5.4.75301)

To bypass Vulkan, all you have to do is set -dx12 to your launch parameters.

• Steam: PEAK > Settings > Properties... > General

• Thunderstore: Settings > Debugging > Set launch parameters

• r2modman: Settings > Debugging > Set launch parameters

• Gale: Settings > PEAK settings > Set custom launch arguments

<details> <summary><i>If you still want to use this patcher</i></summary>

1. Download the Patcher

   Link: https://github.com/CyR1en/UnityPlayerPatcher/releases/download/0.1.1/UnityPlayerPatcher.exe

2. Locate Your Game Directory

   Navigate to your PEAK installation folder where UnityPlayer.dll is located. This is typically:

   [Steam Directory]\steamapps\common\PEAK\
   

3. Place the Patcher

   Copy UnityPlayerPatcher.exe into the same directory as UnityPlayer.dll.

4. Run the Patcher

   Double-click UnityPlayerPatcher.exe or execute the command in the same directory:

   ./UnityPlayerPatcher.exe
   

5. Expected Output

   ============================================
   UnityPlayer Vulkan Bypass
   By CyR1en
   ============================================
   [+] Backed up original DLL as: UnityPlayer_Original.dll
   [*] Searching for pattern: E8 D9 86 F7 FF
   [*] Located CALL instruction at offset: 0x6c73d2
   [+] Patched E8 D9 86 F7 FF -> 31 C0 90 90 90 (XOR EAX,EAX; NOP; NOP; NOP)
   [*] Bytes at offset 0x6c73d2: 31 C0 90 90 90
   [*] Vulkan bypass patch applied successfully to: UnityPlayer.dll
   
   Press any key to exit...
   

Restoring Original Functionality

1. Delete the patched UnityPlayer.dll
2. Rename UnityPlayer_Original.dll back to UnityPlayer.dll

</details>

How It Works

Technical Implementation

The patcher employs binary-level modification to intercept Unity's graphics API selection process during the handling of the "force-vulkan" command-line argument. Here's the technical breakdown:

Target Pattern Identification

The tool searches for the specific byte sequence E8 D9 86 F7 FF, which represents a CALL FUN_1806406b0 instruction in the UnityPlayer.dll binary. Based on the surrounding code context and execution flow, this function call appears to be part of the Vulkan activation pathway, though its exact purpose is inferred from the assembly analysis.

Assembly-Level Modification

; Original instruction
E8 D9 86 F7 FF    CALL FUN_1806406b0

; Patched replacement  
31 C0             XOR EAX,EAX     ; Set return value to 0 (failure)
90                NOP             ; No operation
90                NOP             ; No operation  
90                NOP             ; No operation

Execution Flow Modification

1. Before Patch: Command-line parser detects "force-vulkan" → calls unknown function → if successful, presumably sets Vulkan-related flags
2. After Patch: Command-line parser detects "force-vulkan" → function call bypassed with failure return → Vulkan forcing pathway interrupted

Compilation

Requirements

• CMake 3.10 or higher
• C++17 compatible compiler (Visual Studio 2017+, GCC 7+, Clang 5+)
• Windows SDK (for filesystem operations)

Build Instructions

1. Clone or Download Source

   Ensure you have the project structure:

   UnityPlayerPatcher/
   ├── CMakeLists.txt
   ├── src/
   │   └── main.cpp
   └── README.md
   

2. Compile the Project

   cmake --build build --config Release
   

3. Locate Executable

   The compiled executable will be available at:

   build\bin\release\UnityPlayerPatcher.exe
   

Safety Considerations

• Game Integrity: The patch only affects Vulkan forcing; all other game functionality remains intact
• Reversibility: Always keeps original DLL backup for easy restoration
• Anti-Virus: Some AV software may flag binary patchers as suspicious (false positive)
• Open Source: The patcher is open source to verify that it's not doing anything malicious.
• Automatically Built Executable: The executable in the release section is built and uploaded through GitHub actions. The executable is not manually uploaded from my computer, thus making sure that it only contains functionalities that can be viewed publicly.

License and Disclaimer

This project is licensed under the MIT License.

This tool is provided for educational and compatibility purposes. Users are responsible for compliance with applicable software licenses and terms of service. The author assumes no responsibility for any damage or issues resulting from the use of this patcher.

Important: This tool modifies game binaries. While designed to be safe and reversible, always maintain backups and use at your own discretion.