So I finally got the overlay to show up, but once it does it's not responsive to any clicks, it seems like the game is still in focus and it's receiving the keyboard input instead of the steam overlay, pressing shift+tab doesn't close it.
I remembered the Big Roundup post mentioned adding --in-process-gpu if the overlay is not showing, though it did show I thought giving it a try and it works.
Ashley did it work for you without it? you might want to add it to your installation instructions.
Also it seems to work for me with badpad.exe and not just nw.exe, is there something specific I need to test that might not work and come back to bite me in the ass later?, or if it's showing up then it's all good?