The best comparisons are probably Lost and Westworld. I've never watched Lost, but Castle Rock sounds similar to it with unraveling a mystery, plus J.J. Abrams has been involved with all three shows. I'd say it's less... complicated to understand than Westworld is, though.
Castle Rock uses some of Stephen King's mythology for an original story, and it's apparently going to be an anthology series, so different stories each season. After seeing your trepidation with Hill House, I think you'll like it as it's technically listed as horror, but veers more toward sci-fi/thriller.