At least some of the Halo games used Orleans as part of the multiplayer backend: https://github.com/dotnet/orleans https://github.com/dotnet/orleans Orleans c

At least some of the Halo games used Orleans as part of the multiplayer backend: https://github.com/dotnet/orleans https://github.com/dotnet/orleans Orleans can run on .NET Core now, but I don't believe .NET Core existed when those backends were first created. So they would've been running under the full .NET Framework on Windows.