The gimmick on offer: you can choose to play in first, second or third-person tense, and past or future tense. It's neat, but the game is so much fun to play (in any tense) that the experimental aspects of this technical wizardry are overshadowed (I chose to play in first-person past tense, which gave a nice "wartime memoirs" feel to proceedings).
The cliche horror-style opening doesn't bode well, but once inside the "old dark house" it really takes off. Not one, not two, but *three* well-implemented, well-characterized NPCs who are not only chatty but can take the initiative to direct conversation, and can wander around the house like real people. Lots of detailed scenery descriptions, solid parsing, gentle puzzles, and a cracking yarn to boot. Go in blind, and you will really have no idea where this story is leading. I was expecting further twists and revelations right down to the very last turn. Play it.