Arborea

The aptly named Arborea starts off as you enter a simulation of a Vast Forest. Setting a game in a simulation is a great IF trick that immediately circumvents certain common hurdles in text adventures.
It easily explains away the immediate proximity of the fjords to the desert and other geographical oddities for one.
Placing the protagonist in an obstacle-filled simulated world unknown to them mirrors the player's motivation in solving the problems in an oldschoolish puzzle romp such as this game. Just tackling the puzzles you encounter because they're there gets an extra layer of explanation (or a slightly more believable handwave) as "This is what the simulation throws at you. Now deal with it."
And of course, a sim offers a great opportunity for a short but nice (Spoiler - click to show)XYZZY joke.

The simulated geography is convenient for the in-game traversal of the terrain as well as for the player's out-of-game map making.
It's a compass-based hub-and-spokes design, where the spokes are subdivided in a limited number of locations (usually no more than three or four).
The different areas are not self-contained. Puzzles in one area often need wisdom and objects obtained in another. This necessitates several traversals of the map. At least one exploratory round to find and research all available obstacles, pick up anything that is not nailed down, and take notes about how to approach the different puzzles and in what order. A lot of associations and ideas for a strategy will pop up in the players head during this stage.
Solving the game will require a few more rounds of going back and forth as new locations open up. I never felt completely lost, as repeated exploration gave me new ideas, and there were always a few spokes I could try these ideas in.
Although many of the puzzles are tightly interconnected, the game is not completely linear. Several of the spokes contain loose objects, with nothing restricting the player from taking them. These can all serve as that first loose thread to start pulling and get the ball rolling.

The puzzles themselves are varied. Some use of machinery, some manipulation of NPCs, plenty of variations on the classic lock-and-key theme.
The difficulty will probably depend a lot on how the player's brain is wired and their experience with oldschool games. The hardness of the problems mostly relates to the level of associative thinking is needed to intuit the solution. Many times straightforward application of real world knowledge will prove successful, other times the player might let their mind drift and use a certain kind of "moon logic" to make the necessary leap of imagination.
I found that there were plenty of clues available in the text. However, recognizing them does need the player to tune in to the game's style. As the pointers appear in the natural flow of the descriptions, the evocative writing can sometimes obscure a clue hidden in the middle of a descriptive paragraph.

The descriptions produced some very vivid images of the surroundings. I was impressed with how well each spoke's central theme (Serengeti Plains, Caribbean Island,...) was brought to life in just a few locations, implying a much broader world than was accessible to the protagonist. Very strong writing in this regard.
Arborea's writing is less successful in maintaining a consistent atmosphere. There are several voices present in the game's text, and the discrepancy between their respective tones felt somewhat jarring at times.
There is the simulation speaking. It welcomes you as you enter the sim and consequently introduces each new area as you discover it. I imagined this as a pleasing, soft-spoken and caring voice, even poetic.
There is the somewhat more distanced game narration, which provides the colourful, evocative and immersive descriptions of the landscape.
And there is the fourth-wall-breaking voice of the author. Sometimes this is a justified interruption to clarify game mechanics, but often it jumps in unannounced (in the same font as the narration) with a "funny" aside to the player (or is it to the PC?). This broke the atmosphere of the game on several occasions for me. Perhaps a nod to the snarky comments to the player in old Infocom games, but not so well placed here.

Overall, Arborea carries a gentle ecological message about the beauty of nature. In particular, it tells of the wonder of trees, and of mankind's varied attitudes towards them in different time periods and different cultures. There are depictions of careful, even reverent co-existence with trees, practical use of them for our daily commodities and also the destructive use of them in a mass-production way of life.
This loving attitude toward trees is frequently at odds with the oldschool adventurer's amorality toward the NPCs. It's impossible to solve Arborea without behaving questionably toward the other people you meet. Sometimes in a mostly innocent and funny trickster manner, other times actively misleading them and abusing their trust, or even drugging them to get what you want. I couldn't bring myself to comfortably reconcile this behaviour with a peaceful problemsolving exploration.
All I could do was think: "Hey, it's a simulation." And this got me questioning what this simulation was actually for. Is it a educational program about our planet's history? Or just a game people in the future play for their amusement?

The game characters are basically beautifully painted cardboard cutouts. They're great to meet in their intended role, but once you start interacting with them, there is not much substance to them. I would have liked for them to bit more talkative or even gossipy. It would make them feel like more rounded characters in their own right, and it would be an opportunity to add to the sometimes hard-to-pick-up clues in the text.

The endgame feels like the game does one last loving nod back to its precursors. It's essentially a condensed old school puzzle romp; an almost carnivalesque obstacle course with all kinds of puzzles strung together in the final straight line to the exit. A great way to bring such a broad and sprawling game to a close.

I spent about six hours in Arborea, and I loved the ride.