Using TorchSharp & RLMatrix in Unity

NOT RECOMMENDED

Many users, myself included, have noticed weird and unexplainable behavior of TorchSharp in Unity. The performance is sub-par and the behavior of garbage collection is unpredictable. If you’re planning on using RLMatrix inside a Unity application, we recommend using the networked version of RLMatrix - you can run it on the same machine via local socket and the performance will be much better. Alternatively, consider using Godot Engine which supports .NET Core and demonstrates INCREDIBLE performance with shared-memory TorchSharp and RLMatrix.

So you REALLY to use TorchSharp in Unity 2025?

The TorchSharp contributors could probably explain this in much better detail than me - but essentially installation steps involve downloading libtorch DLLs (over 1GB) and installing/referencing them.

This is done automatically in newer .NET Core versions, but as Unity is yet to move to CoreCLR, we have to do many steps manually - including the NuGet installation. I’ve made a guide before on the effective way to install NuGet packages in Unity; this short guide just extends it with manual copying of the DLLs.

1. Create required folders in your Unity project:

Assets/Plugins/Windows/x86_64

2. Install RLMatrix using NuGet

First, download nuget.exe from the NuGet website and save it to C:\nuget.exe. If you save it elsewhere, make sure to update the path in the script below.

Save the following PowerShell script as install-rlmatrix.ps1 in your Unity project’s root directory:

$packageName = "RLMatrix"
$packageVersion = "0.4.0"
$netTarget = "netstandard2.0"
$tempDir = ".\Temp"
$dllDir = ".\Assets\Plugins"
$nugetPath = "C:\nuget.exe"
if (!(Test-Path $nugetPath)) {
    Write-Error "NuGet.exe not found at $nugetPath. Please ensure it's installed there or update the path."
    exit 1
}
if (!(Test-Path $tempDir)) {
    New-Item -ItemType "directory" -Path $tempDir
}
& $nugetPath install $packageName -Version $packageVersion -OutputDirectory $tempDir
if (!(Test-Path $dllDir)) {
    New-Item -ItemType "directory" -Path $dllDir
}
Get-ChildItem -Path $tempDir -Directory | ForEach-Object {
    $packagePath = Join-Path $_.FullName "lib\$netTarget"
    if (Test-Path $packagePath) {
        Get-ChildItem -Path $packagePath -Filter "*.dll" | ForEach-Object {
            $destinationPath = Join-Path $dllDir $_.Name
            if (!(Test-Path $destinationPath)) {
                Copy-Item -Path $_.FullName -Destination $destinationPath
            }
        }
    }
}
Remove-Item $tempDir -Recurse -Force

For more details on how this script works, see: https://www.nurupo.io/posts/unityhowtonuget/

3. Run the PowerShell script

This is conveniently done by right-clicking on the .ps1 file in windows explorer and selecting “Run with PowerShell”.

4. Get TorchSharp native DLLs

Copy all the TorchSharp DLLs to Assets/Plugins/Windows/x86_64. I copied these from a .NET 8.0 project I had around that was using TorchSharp.

5. Configure DLL import settings in Unity

For each DLL in the Plugins folder:

• Select the DLL in the Unity Project panel
• In the Inspector, ensure settings match the following:
• Set Platform to “Windows”
• Set CPU to “x86_64”

Done, this should work!

Note

If you know a less clumsy way of getting this working, please contact me through the RLMatrix Discord or GitHub.