It's what some people these day are calling a "walking simulator", though I tend to think of it more as a collection of short stories told in an interactive medium where the environment is both the setting and the story teller. You play a young woman, just come come from university to find the family home empty and basically spend the whole time exploring the house, reading/listening to various letters and ephemera that tell the story of the people that live there.
There are some basic "gamey" puzzle elements, though that's mainly to unlock new areas of the house and ensure you 1) explore thoroughly and 2) get the various story pieces in more or less the right order.
Personally I really enjoyed it and I think it's very well done, though I understand why it's not everyone's cup of tea. Don't go in expected a creepy jump-scare experience, which is what I think some were expecting from the promotional material. The stories are very personal ones and I found it a nice way to spend a few hours, but don't expect any real replayability beyond that.