Inside (game) (no spoilers)

A friend of mine emailed me about this game, noting that she'd seen reviews that said "buy and play and don’t look at reviews first so you get the full wonder of it" - and so I did.

The game starts with a boy, in a forest, who starts to run right...and that's about all I'm planning to tell you about the details of the game.  It really is a game that will reward discovering what happens by yourself.
"Creepy mindfuck" is the most common description I've been able to find for that game...and that fits well enough.  It certainly is an incredibly tense and atmospheric game, with good, mostly not-too-difficult puzzles and multiple moments of wonder, awe and horror.
I'm so-so on the ultimate ending, but this game was definitely more about the journey than the explanation.
You'll get about four hours worth of playtime out of it - and for those without the budget/inclination, this is a game which will probably be enjoyable to watch a few Let's Plays (especially a couple of the more shocking bits).

Potential spoilers in any comments, so if you haven't played don't read them just in case...