One of the oldest IF titles ever written (its first version was written in 1979 for the IBM 370 mainframe under the name Brand X), Philosopher's Quest gets my vote for having the most unfair first puzzle ever in a game.The plot starts out intriguing enough: with you wishing you hadn't waved that old magic wand you found in the junk shop off Market Street. For when you did, the atmosphere turned inside out, taking you with it. And when it turned back again, the shop -- and the shopkeeper were no more...
Philosopher's Quest pioneers the concept of a "pure puzzle" IF-- games whose emphasis is on (very difficult) puzzle-solving than on plot and character development. The parser is very primitive, and won't recognize even common verbs such as EXAMINE (curiously, every Topologika game suffers from this, even years after the original parser was coded). This makes the solution to the first puzzle even more frustrating (hint: try to GET something that will help you out, though you can't see it anywhere in the description. Yeah, that's why it's a ridiculous puzzle). The game does have good writing and some clever puzzles, but you'll likely be too frustrated with the parser to get much enjoyment out of it.