➡️ See updated How to use below ⬅️

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.

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.

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

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:

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.

; 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

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

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

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
   

• 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.

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.