Moonmist

Moonmist is a short introductory level adventure whose unique selling point is that it offers four mysteries in one, based on the "favourite colour" you state at the beginning of the game. (Actually only green, blue, red and yellow are routes -- anything else puts you on a random path).

Each of these mysteries involves the same cast of characters and tasks you with three goals: finding a hidden treasure (after finding several clues to lead you to it), discovering the true identity of a "ghost" that has been haunting the castle you're visiting, and determining the truth behind the death of the castle master's former fiancee.

Each route does unfold a bit differently, and there are even a couple that look like they might be going in the same direction before making it clear that no, something different happened this time around. But it's all over a bit quickly; even taking into account how this is an "introductory" adventure, a single playthrough is very short indeed, and there's not a lot of what one might call "puzzles"; the most complex things get is knowing which rooms or objects to search based on people or notes making vaguely obtuse references... and knowing that in most cases you'll need to search things multiple times.

But while it lasts, it's a fun, atmospheric romp with some entertaining characters (including, in one of the routes, an almost-openly gay character, which was probably revolutionary at the time), with its main drawback being that a good half of the room descriptions are in the feelies; you'll know this by the immortal phrase "it looks even lovelier than it sounds in the tourist brochure". Whether this was done as copy protection or simply to encourage you to engage with the well-crafted supplementary reading material in the feelies I can't say; just be aware that you will want a printout or electronic copy of them to hand while you play.

Moonmist isn't a classic like some of Infocom's other stuff. But approach it as a set of short story palate-cleansers and you'll have a good time with it.