Considering that this is only the second Age I've played in Seltani, I may not be equipped to judge the format. But I have played the Myst series, and Riven is my all-time favorite game, so I have some experience to rely on -- for good or ill.
Salvanas does capture that classic isolated-explorer-tinkering-with-strange-machinery ambiance from Myst. It's actually more than a single Age, since it contains five different worlds interconnected via linking books. Each world features a different puzzle. Some of these puzzles are more successful than others.
The home world itself, which links to the rest, is a series of rusted platforms suspended over bubbling mud in a caldera. Abandoned industry reclaimed by nature is such a key atmospheric note in Myst (and Riven especially), and here it's done justice. It's sparsely described but effective, and the puzzle to unlock the other linking books, which involves setting sliders to match a code, strikes about the perfect difficulty balance for my tastes. You have just enough configurations to keep your mind turning them over until, click, you've solved it.
Discovering what awaits you in the other four Ages is part of the game's charm, so I won't spoil that by describing their details. What I will say is that one world, whose puzzle heavily features a stream, worked for me just as well as the home world. Perhaps better. The others... not as much.
One world's puzzle involves extending and retracting catwalks and ladders to reach different locations. The environment here is lovely but the puzzle's goal is obscure, because the player doesn't know exactly which location they need to reach until, bam, they've suddenly reached it. You essentially fiddle with opening different pathways until you stumble into one that lets you win.
Another world's puzzle is something I would just consider cruel. Its solution hinges around an ocean's tide rising and falling, and the tide does this in real-time. The player cannot influence the tide, and indeed, unless the player just stands around waiting, they may not even notice that the tide fluctuates. The only reason I noticed was because I kept the game open in my browser and fortuitously glanced back at the right moment. But even once you do notice that the tide can change, you still only have a few opportunities in which to solve the puzzle. If you fail, you'll have to wait until the tide rises again. For me, that meant turning the game off and waiting until another day -- and then waiting again while I did something else for an hour because the tide was still in the wrong place when I restarted.
Maybe this is common in Seltani, and some Ages are meant to be changeable landscapes that players can return to throughout a twenty-four-hour period to discover new features. In that case, my criticism is empty. Otherwise, I found it very frustrating, especially since it was the only puzzle in Salvanas to feature a real-time mechanic.
Salvanas has a fifth Age that you can access immediately from the home world. You can do nothing here, but this Age changes slightly (and I do mean slightly) when you solve all the puzzles in the other Ages. I thought there must be something more to it, but after poking around without success, I finally searched for hints only to find a comment by the author stating that that was the end. The game never pretends to have a story behind its puzzles, but this was still an anticlimax.
However, despite my qualms, I would recommend Salvanas for both puzzle-fans and Myst-fans. It has enough positive qualities to outweigh the negative, and I think it would be more enjoyable for players going into it with the right expectations, which is what I wanted to provide with this review.
As for Seltani itself, that's fantastic, and I look forward to exploring more Ages.