I love this! Thanks and kudos to the dev.
Was sad to see LiteSwitchX stop working when I finally upgraded from High Sierra, but this more than fills the gap, including quitting an app or closing a window with the very intuitive keys.
Being able to view only the windows for the active app sets it apart from the built-in Command-Tab and even Mission Control / Exposé. Yes I know that Ctrl+Down Arrow does the same, and I could easily set a shortcut fn key, but Exposé windows aren't gathered neatly into one panel they way they the are with AltTab.
Also having two two key combos for two different modes is sheer genius.
This may well be my first 5-star review. Bravo!