Shade is one of those classics that get recommended anytime anyone recommends any IF to newcomers: it's brief, disquieting, ambiguous, memorable without being especially difficult. It offers an interaction style too guided and fluid to be called "puzzly", and which probably belongs in some other category. It threatens one's ideas of the relationship between the player and the protagonist. It has entered the canon, as far as interactive fiction has one.
In a lot of ways these are the hardest works to write about. Shade has already received analysis all over the place, from long discussions on rec.arts.int-fiction to a scholarly chapter in Second Person. People have written about the sense of oppression the game creates; about the relentless emphasis on light and darkness; about the way the player is coopted into working (sort of, maybe) against the goals of the protagonist and behaving as though insane. Can Shade, in fact, be grasped by any corner that doesn't have a dozen fingerprints on it?
Possibly not. Good criticism of Shade tends to be pretty spoiler-laden anyway. But here's the pitch I want to make to the people who haven't played it yet, either because they're not IF fans and this is the first they've heard of it, or because the promise of player/protagonist conflict wasn't the sort of idea that made them rush to play.
Shade is the closest I've come to being able to play an episode of the Twilight Zone. It works through dread: we want to know what comes next, and we are certain that it won't be good. But unlike Anchorhead or other Lovecraft-inspired works, Shade isn't about exposing the black writhing heart of the cosmos. It is something more contained and ordinary than that. The classic Twilight Zone ending leaves you feeling like you knew all along what was coming; even if the imagery of the ending is outlandish, the meaning is usually something universal and internal. We all have facts in our lives that we're trying very hard not to see clearly.
Shade is about one of those facts.
N.B.: Unlike some of the interactive fiction we've covered, Shade is readily playable online; but anyone who wants to download the game file for play offline can find it at IFDB. Also perhaps interesting is Stephen Granade's introduction to playing IF, which introduces standard commands.