The problem with building a .NET (classic) executable that runs on both clean Windows 7 install and on Windows 10 is that Windows 7 only ships with .NET 3.5 inbox and Windows 10 ships with .NET 4.X. A .NET 3.5 executable will not run on a (clean install) Windows 10 directly. It can be coerced to do so in multiple ways, but none of them are "worry-free single file" solutions (config file, registry settings, environment variables, etc.).
One of the solutions is to set COMPLUS_OnlyUseLatestCLR environment variable to 1 before the process starts. This will allow .NET 4.X to take over execution of the program. This still doesn't qualify as "worry-free" because we need a batch file or something else to set the envionment for us before the process start (it's too late once Main is executing).
When I said we need to set COMPLUS_OnlyUseLatestCLR environment variable to 1 bef