.NET Framework
Starting from versions 1.4.9 (including dev and rc builds), the codebase has changed to run on .NET 6 platform only. This allowed to update to the latest version of Monogame (3.8.1), and keep up with other changes and recent development from .NET.
When you downloaded or updated to a recent version, you may get a warning message when trying to start ORTS-MG while no corresponding .NET version is found:
Following the message you will be guided to download .NET 6.0.
Please ensure to select the correct version ".NET Desktop Runtime", not ".Net Runtime" or "SDK" only. In most cases, you will need the x64 (64bit) version, unless your OS is limited to 32bit (x86) or you are running on ARM devices.
Branched off from OpenRails, ORTS-MG is written in C# running on .NET platform on Windows. In the recent past, Microsoft has made efforts to bring .NET platform to other OS platforms as well, starting a whole new .NET platform named .NET Core.
Previously, ORTS-MG has been provided in binary form for both, .NET Framework 4.8, and .NET Core 3.1. The Folder structure in \Program contained a subfolder for .NET 4.8, and a subfolder for .NET Core 3.1 binaries:
Program
|----net48
|----netcore31
By default, starting OpenRails.exe from the Program folder, it will have used appropriate binaries for the .NET Framework found on the system, either .NET FRamework 4.8 or .NET Core 3.1 version.
.NET Framework is a Windows-only version of .NET for building any type of app that runs on Windows.
ORTS-MG had been built against the latest (and last) version of .NET Framework, version 4.8, which is supported on all active Windows Versions (Windows Windows 11, 10, Windows 7 SP1). Aside of bug fixes, there is no new development happen from Microsoft on .NET Framework 4.8.
.NET Core is a free, cross-platform, open-source developer platform for building many different types of applications.
In addition to .NET Framework 4.8, ORTS-MG was fully enabled for .NET Core 3.1.
While .NET Core is platform-independent, ORTS-MG still has dependencies on the Windows platform. However, these dependencies are minimal and the .NET Core 3.1 version had been tested on Linux. Please see the Linux Wine article in the Wiki for details.