There's also a window claiming to be Windows' CMD. As I can't figure out how to enter text in any of these windows (I'm assuming it's disabled, otherwise CHAOS) I can't tell if it's just a vestigial window of if it's a true output.

The topics on the Github repo list both Linux and Windows. The Readme calls itself "aka Monotty Desktop". That makes me think they may have written the code for the Mono runtime, so I'm expecting it's C#.

I had played around with a similar idea in C# some months back, though I was targeting only Windows because it took P-Invoking into some Win32 APIs to get most of the functionality.