Photopia by Adam Cadre is probably his most famous interactive fiction. It was released in 1998 for an IF contest (which it won). I don’t play IF games that often because their puzzles can often be maddeningly obscure, but this is an exception, and is one of my favorite games — it’s not a typical IF game.
As much as I hate when others say this, Photopia is a game that it’s best to go into unprepared for, without knowing what to expect. Expectations can affect the experience. But I’ll at least say that it’s short, very well-written, that it involves only a single puzzle, and that it’s linear. If that isn’t your cup of tea, ignore this post. There are a lot of things about it which don’t make sense until the end. The nature of its single puzzle and its ending are the things people tend to remember about it.
Cadre’s other IF are worth checking out too — he personally feels that his best work is Varicella (also found on that same page), because it is a full world and Photopia is more of a short story, but Photopia is probably better for the casual IF user since it’s less difficult to get into.
TIGdb: Entry for Photopia