Well, I just finished FRACT OSC, and I can safely recommend it. If you were a big fan of the MYST series, like I was, then this is perfect for you.
There is no real story behind this game, and it invites you to use your imagination, to explain why everything is what it is. From the visual and aural feasts you are given, you draw your own conclusions as to what the civilization was like. There is virtually no text within the actual game, instead relying on pictures and diagrams to relay information. Music is heavily used for artistic effect, though many of the puzzles do not require music to solve. Instead, having an iPod or Phone handy to take quick pictures of diagrams is useful.
This game requires an awful lot of backtracking, so be prepared.
Beware, to run this at a constant framerate you need a decent rig, or to turn down the view distance. However, your mileage may vary. The options menu is rather sparse, lacking even a rebind keys option, which forces you to use the default bindings.
This game uses flat textures and polygonal shapes to create the terrain and buildings, and personally, I think it pulls off the look quite well. For such a simple design, it is quite beautiful.
The music creation tool is not something I have experimented with, but if you have any experience with music editing programs, you may find use in some of its synths. Again, your mileage may vary.
In my opinion, this game does not neccesarily warrant more than one playthrough, but if you have the patience to finish the game, you should have the patience to find and collect the achievements. I'm going to be searching for them myself, as I haven't perfected the game yet.
In conclusion, this game is beautiful. The art style is wonderful, but the puzzles are not for the impatient. Many of them require fine tuning and experimentation, and some of the later ones require backtracking. The options menu could do with more, but it is forgivable by a game so pretty.