This is going up front in the hopes of helping someone else - I managed to utterly, utterly miss the point of the game's central mechanic, in which the reader is invited to actively participate by drawing symbols onto their skin, thus dissolving the distinction between player and character. It's implicit in the text, but I'm so used to the experience of a game being purely virtual that I entirely overlooked this, and therefore missed out on an intriguing manner of interactivity. Someday, when the memories have faded, I intend to come back and experience this properly. (Spoiler - click to show) ... And maybe I'll be lucky and met this fabled slime kid, too.
With that said, the game I experienced on screen was so rich an experience that it seemed complete to me. The worldbuilding is deeply, richly apparent, better so than many SF stories I've seen. One is is imbued with the fascination, trauma, and frustration the protagonist finds in - carefully limited - explorations that make up the story's heart.
(Now I'm having a go at Twine myself - my first finished game will have a "makes reference to" credit to this one - and I'm finding that one doesn't appreciate all the subtleties of coloured links and backgrounds until attempting to code. That's the kind of art that works by not drawing attention to itself, and Porpentine is a master at it.)