If you're still interested in reading Gothic novels after finishing Northanger Abbey, the one that it's most directly based on is The Mysteries of Udolfo, which I read as part of the same unit I read Northanger Abbey in. It's a bit long and not as sharply written as Austen (of course), but it was still a fun read.

I actually own the more recent remaster of Pathologic; I had to pick it up after reading Rock Paper Shotgun's 2008 "Butchering Pathologic" article, but I've yet to get up the nerve to actually play it, given how famously draining it is. Maybe I could stream it, but I'm not even sure how much fun it would be to watch!