So this is interesting: Normally a Windows program (executable) if you try to run it anywhere else will show a message “cannot be run here” and terminates.

Printing this message is actually done by a little program whos task is to only print out this very message. So it can be overwritten.

Michael Strehovský did exactly this, very impressively. He documented what he did to get the game “snake”, written in C#, running on DOS instead of the “does not run here” stub. In an executable file that would run both, on standard 90s MS-DOS as well as on Windows with the .NET Framework installed.

He used a quite elaborate toolchain – namely DOS64-stub.

You can read all of this in the full thread. I recommend a deeper dive, as it’s a great start to better understand the inner workings of your computer…