Simply put, this is my favourite game of all time. Don't read any more reviews and spoil the game for yourself, just go and play it because there's no experience like going into the game knowing nothing about it.
To progress in this game, you don't complete levels or unlock new tools. The progression is lead by the knowledge you gain from playing the game and discovering new revelations.
It's an open world game and I'm not a fan of open world games but this feels so different to any other open world game because it has been so carefully crafted and so much thought has been put into every single aspect of the game. The worlds are small but are so packed full of things to explore.
Everyone plays the game differently and discovers things in a different order so everybody's experience is entirely unique.
The game is beautiful. That includes the locations, the soundtrack, the unfolding story, the physics and gameplay mechanics. It's all great.
I don't normally enjoy DLCs, as they're usually just moneygrabs but the Echoes of the Eye DLC is most definitely worth getting too. It's like an entirely separate game within the game, with many additional gameplay mechanics, a full game worth of stuff to discover and some light horror elements, giving you a very different but equally amazing experience.