Avernum 3: Ruined World, weirdly enough.
It’s clunky and quite dated, at least from a graphical perspective (plus everything is pretty tiny at my resolution), and also from a design perspective I guess. It’s not something I would recommend for other people, but there’s just some weird charm about it that keeps me playing it. The exploration is fun, combat is quick and somehow feels… satisfying? And it’s definitely not an overly curated experience hand-tailored for focus groups.
I do play it with a walkthrough, that’s just how I am, but it’s been pretty fun. I’ve played through Avernum 2: Crystal Souls before, but that was 7 years ago now.
FWIW those have a lot of overlap, it’s not unique subscribers. Plus there’s a couple of default subs included.