Shadowgate I admit I have never even heard about this game before it appeared on the GOG main page, yet it immediately drew my attention for its peculiar style in both art and gameplay; searching around on the Internet made me aware that this game is a remake from a very old (1987) Mac game then ported on other platforms (NES included) which gained a “cult” status.
How much has the remade title retained the old-school values of its ancestor, though?
After having played it, in my opinion the answer is obvious.
Shadowgate is a point and click adventure in first person perspective: you take the role of the young Jair Cuthegar, an inexpert warrior following the call for help coming from a mysterious robed figure appearing in his dreams.
His task is to travel to castle Shadowgate, the former stronghold of the Circle of Twelve (an order of powerful mages), now conquered by a malevolent Warlock who promises to move death and destruction form there, drawing an immense amount of power from somewhere in its depths.
The mechanics have been largely untouched, allowing the players to choose from several different actions (much like in the earlier Lucas Arts adventures) presented as verbs to interact with almost everything they can find in the castle.
Unlike Lucas Arts titles, though, this time there will be plenty of ways to horribly die and waste your progress, and you also have time limits: each action requires a turn, and after a fixed amount of them (I don't know the precise number, as the game does not precisely inform you on how much time you have left) you can either be killed by a curse you have been victim of -if you are not fast enough to cure it- or fail in stopping the Warlock, who brings his plan to fruition.
The difficulty of puzzles and the time limits are set when you choose one among the four difficulty levels; the developers made sure to craft a system where every kind of player could be satisfied.
On “Normal” the game will treat you like a total noob, mostly giving away the solution for each of the extremely simplified (and reduced in number) puzzles; on “Apprentice” the difficulty scales up a bit, forcing you to use your brain and transforming torches in consumable items; on “Journeyman” your time limits and torches run out much faster, and you can finally have a good challenge that requires thinking to be overcome, presenting tough but fair puzzles with a good amount of subtle hints to help you navigate the Castle; on “Master” you'll face total insanity with the only aid of torches that run out like matches.
My personal recommendation is to play it on “Jouneyman” (the closest experience to the original, it seems), as each puzzle will give you plenty of satisfaction by always being reasonable and without ever being too difficult or unfair while also avoiding to hand over the solutions;
the high quality of the riddles, the good level of challenge, the compelling and atmospheric hand drawn screens, the evocative soundtrack, the great voice acting and its respect for the player make Shadowgate one of the best adventure games you can find on GOG, imo. “Normal” mode is useful if you are having difficulties in understanding what to do next but you don't want to use a guide: that way, the game will point you towards the objectives and give you the location of some of the most important items you need without spoiling the riddles. I suggest to start two “parallel” games (one on Normal and one on Journeyman) to get the most out of the game.
My only complaint is that the “Master” difficulty level is absurd. You could take everything I wrote until now and reverse it: you have so little time to do things, you are left completely clueless and the solution of several puzzles are so nonsensical that they draw all the fun out of the game.
In any case, the “sane” modes are so good that they make the last one completely irrelevant, so you will lose absolutely nothing by skipping (or dropping, as I did) it.
I can definitely vouch for Shadowgate's quality, and I recommend it to everyone -especially to every adventure fan out there. I'm also eagerly waiting for the sequel (the remake of “Return to Shadowgate”), announced for 2016 after the end credits. 
