Kitty Horrorshow's version of Hell is part unsavory criminal underworld (with its own infernal power struggles), part vicarious thrill ride, and 666% compelling IF experience.
Stygia throws players straight into the action with a well-defined mission sequence (Spoiler - click to show) -- a contractual haunting, including some playfully sadistic options, before segueing into a colorful exploration of the title setting. It has plenty of familiar narrative elements, seemingly influenced by adventure games (Grim Fandango), film (Beetlejuice), TV (American Horror Story), and comics (Mike Carey's Lucifer). But it plays with these tropes uniquely enough to feel like a novel experience.
The whole effort is well-suited to the text-heavy, hyperlinked Twine format -- the descriptions set the mood effectively, while allowing your imagination to fill in the blanks.
The replay value seems a bit limited -- the whole thing feels like a self-contained 'pilot episode', with variable hows all leading up to the same what. But i'm willing to overlook that: merely experiencing the game's setting is so compelling that it doesn't need multiple playthroughs to satisfy.