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Run managed code before Unity does!

Unity Doorstop

NOTE: Version brought some breaking changes to how command line arguments are passed. Refer to the release changelogs for more info.

Doorstop is a tool to execute managed assemblies inside Unity as early as possible!

This repository is indented mainly for developers!
Developers should package Doorstop into their applications for the end-users.


  • Runs first: Doorstop runs its own code before Unity has an ability to do so.
  • Configurable: A very basic configuration file allows to specify your own assembly to execute!
  • Public domain! You are fully free to embed Doorstop into your application!

Guides for users and developers on the wiki


To build, you will need:

  • PowerShell 2.0 or newer
  • Visual Studio 2019 (2015 might work as well with some modifications)
  • Visual C++ Toolset v142
  • .NET Framework 3.5 or newer (only for the example, not used by the proxy)

Clone, open in Visual Studio, select the platform (x86/x64) and build.

Custom proxy functions

Doorstop's proxy is flexible and allows to be load as different DLLs. You can modify which functions are proxied by adding/removing entries in dll.def

The current set up allows to use the proxy for the following DLLs:

  • winhttp.dll (All exports, works better with Wine)
  • version.dll (All exports, better support for Unity 3)

Simply rename the Doorstop DLL to use it as a different proxy (as long as the exports are included).