Project1337 is a Win32 program that blocks off the screen with black upon request until a specific set of keys is pressed, currently Z, P and ` in that order. More information is available in the dialog that appears on startup.
I'm sorry to say that I'm not aware of how to build this on the command line. To build graphically, use Visual Studio.
If you need to build it on the command line, then you can try building it by
linking it to comctl32.lib.
Project1337 is licensed under the JSON license. See the LICENSE file for more details.