I played Mystique Ch. 1 "Foetus" and liked it quite a bit. The controls are extremely clunky, and the story is as cliche as you can get, but the atmosphere and puzzles were interesting enough to keep me playing. Ch. 2 is 0.99, but before buying it I wanna know how long is it (it took me around 20 minutes to beat the first, which was a free download) so I hope the second is way longer.
Depending on how adept you are at solving the puzzles, probably about an hour or two. Bear in mind though that this is an episodic game, so the individual chapters aren't suppose to be long.
I beat chapter 1 in 10 mins, chapter 2 took me about 80 mins but I was stucked for about 20 minutes because I missed one item. Would be around hour if I would found that item at first