Every aspect of the game is gloriously hand crafted. Writing, graphics, sound, etc. But I think what makes RDR2 unique is that it really transports you to a particular point of space and time through the eyes of a character. Visually it's very cinematic, but I feel it's much closer to literature in the way it immerses you into the world, the characters, and the conflicts.

Personally, I've never seen a game with this focus and this level of scope and quality.