You're irrationally afraid of spiders, heights, sounds, and the dark, and you wake up in the middle of the night, completely unable to move around your house normally because of your fears. You end up conquering your fears in a series of episodes--one of them seemingly a flashback, two others apparently dreams--triggered by various objects you encounter in your house. The way in which the flashbacks are triggered is a bit tortured, but it's a minor sin--the episodes themselves are imaginatively done, with reasonably logical connections to your various phobias.
The atmosphere is nicely done: the game doesn't so much portray a scary setting as portray an ordinary setting, with details magnified out of proportion. E.g., "You feel suddenly claustrophobic as you hear a rustling nearby. What lurks in the shadows, waiting to pounce?" Sometimes, the events that set off your alarms are entirely internal: "As you try to compose your mind, dark memories wash over you: explosions, death, the tolling of funeral bells, gloom, isolation." Arguably, this is one of the few works of IF where the PC's mind is as well rendered as the physical setting. If there's a flaw, it's that you don't get much about *how* you became so mentally crippled--there are vague allusions to memories, but nothing concrete. It seems like confronting whatever caused the fear in the first place would be both more effective and more interesting, in terms of characterization.
Most of the puzzles take place in the phobia episodes, and they aren't easy; a few of them, in fact, verge on the unfair. The worst case involves an object that you have to destroy in order to use--and it's an object that seems like it would be useful in its original states for solving the puzzle at hand. The solutions are logical, but in a few cases in particular, there isn't much in the game to signal that you're on the right track, so things are harder than they should be. Adding to the difficulty is a guess-the-syntax problem in one episode that may prevent you from realizing that you're on the right track even when you are. The last puzzle suddenly introduces a time limit, and it's a pretty tight time limit at that--you're likely to miss it a few times while you're figuring out what the game wants of you. There's a comprehensive hint system, so the problems aren't intractable, but it'd be nice if the game's execution were as good as its concept; puzzles as hard as these risk requiring so much mental energy of the player that he/she loses sight of the plot, which is the best thing the game has going for it.
The concept is good enough to overcome the game design problems, though, and it's not simply an excuse for outlandish puzzle settings. The PC's neuroses are sufficiently real that failing to do certain things to keep them at bay actually kills you; saying "snap out of it" to the PC isn't an option, of course. In that sense, you're forced to be the character in a way that's still uncommon in IF (and was even more so in 1996, before experimental IF was in vogue). The vividness of the setting lies not in what you see but in how you experience it--i.e., through the eyes of the phobic PC. It may not sound revolutionary, but getting the player to focus not on the PC's external goals but on the internal barriers he has to clear represents a real shift in goal-orientation--and even if the puzzle-solving gets projected into external tasks, it's still worth pondering. (That is, you don't actually delve into your own head, a la Losing Your Grip--though one scene comes close. But what's in your head is sufficiently close to the surface throughout the game that your puzzle-solving is almost the same thing.)
As a set of challenging puzzles or as an exercise in atmosphere, Fear works, on the whole--well enough to be worth rediscovering five years later.