What's really interesting about P.T. is the liberties we afford to something that isn't just unfinished, but absolutely unfinishable. It's essentially a palette of ideas implying the shadow of a far more elaborate and terrifying whole (which we'll never get to see anymore of) - and if that isn't an ironically meta expression of what makes classic Horror work then I don't know what is.

A part of it is in the execution – P.T.’s ideas are braindead simple, but they’re represented in a very fittingly-and-convincingly photorealistic way that continues to age quite well. It isn’t really meant to surprise or refresh more than precisely evoke a familiar feeling and aesthetic.

This means that people can freely acclaim P.T. as essentially perfect, since it's a clean execution of setup for a nonexistent whole – just the fun parts. It has no time to run out of steam or to overextend and compromise the uncertainty of its world and rules. It's an island of ideal horror tropes sharpened and angled towards nowhere, unburdened (mostly) from narrative, meaning and interpretation. Where a full game would likely introduce more certainty/specificity in interpretation so as to appear cohesive, P.T. gets to relate on a slightly more direct level to each player's understanding of its sharply-imagined classic imagery - just the scares, the atmosphere, the thesis - and that purity is worth something.