Yes it's a Myst-like, and a pretty good one too. It's not just cribbing ideas from Myst, but feels like it's in conversation with Myst. If you were ever bothered by how Atrus is positioned as a good colonialist (who's still finding new worlds and ripping up their resources to build his own machines and change them irrevocably, but he means well so that's alright), then Quern feels like a deconstruction of that idea, following the train of thought to its terminus. I won't say the plot is brilliant, but it is trying to do something interesting with its influences.

Puzzles are pretty good, on the whole! Quern promises reusable puzzle mechanics, and those are the best of the bunch - they have that Metroidvania quality of getting a new toy and having your mind run through all the places you could try playing with it. A handful of Myst-like big-machine puzzles and a few stock logic puzzles are thrown in for variety. They're not always integrated plausibly, but they're appreciated.

The puzzle structure is very linear. Quern gets away with this in the first two thirds of its runtime as you run around the whole map reconfiguring it with every new reveal, but slips up with an endgame that feels more like an obstacle course than an actual place.