I've tried a lot of mac apps and certain features of some have stood out to me, I found this functionality in BTT and I wanted to make it a seperate app.
Right clicking the red button on the top right of any window does nothing, this app will add functionality so you can quit just by right clicking that app.
I view this as an essential feature for macOS and because of that MouseQuit will be written in swift and made as lightweight as possible so it runs in the background smoothly. I've personally found this functionality very intuiutive with an external mouse and it gives manual control back to the user.