Shade

"A one-room game set in your apartment."

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's extremely well crafted and very, very creepy; this is a "mess with your head" IF par excellence. There's also a lot going on, in a sense, so you may want to replay it a few times once you're done