I'm an old man. If I were to write out everything good about this game I would be long dead. If I wrote out everything bad about this game, it would probably only be a one sentence review.
It may sound cliched but RDR2 might very well be the best PC game I've ever played and I've been playing them for over 30 years. I rank a few games as memorable in that years later some of their scenes still live with me. Gabriel Knight: The Beast Within, Bioshock Infinate and Elder Scrolls Oblivion come to mind.
For me, RDR2 had so many scenes and situations that will stay with me. It reminded me a lot of Witcher 3:Wild Hunt in terms of environment and mechanics but even though I thought Witcher 3 was exceptional, I cannot remember a single thing about it that really stuck with me.
The main protagonist, Arthur Morgan, is an exceptional outlaw, but I always felt this was the life he was thrown into as a child and he does feel some reluctance, Sadly, it seems, he just doesn't know anything else. I say that because the conflicts and choices he has presented to him does have some impact--mainly along the lines of rewards for being benevolent.
Showing kindness is within his soul and he often displays it at certain points. For instance, he meets up with a widow who accidentally killed her husband with poisonous berries. She is so grief stricken that she refuses to leave the wilderness where their homestead is and she has no idea how to help herself. It's a small thing, but he teaches her to hunt, shoot and skin which allows her to stay where she is. It's an interesting dichotomy because so much of the game is extremely violent.
The bottom line is what makes this game so special is that the acting, animation and voice overs are so exceptionally well done that each character is unique in its own right and the main characters almost feel alive and real. You actually care about what happens to them.
The soundtrack is special as well. Song after song has a certain sadness and inevitability to them. Judge for yourself and listen to the songs on Youtube especially Unshaken. This is award winning music, not just video game music.
There's so much good here that it's hard to list it all. The main story can be played straight through but I spent a significant amount of time on the mini games-- poker, blackjack, dominoes, fishing, hunting, and even five finger fillet (sans Aliens 2). They are not only fun but challenging. As it is an open world, I can say this--it is a bit satisfying to put a bullet in the head of a guy who is cleaning you out at the poker table.
However, just be aware, murder and criminality will bring bounty hunters down on you and death can be costly.
So with that, it helps if you like open world adventure games and if you do then this is best of breed and an amazing achievement. Also, if you do play through, WATCH THROUGH THE END CREDITS! They are somewhat intriguing because they provide a segue to the first Red Dead Redemption as you see RDR 2 is a prequel to that console only game. (PLEASE PORT TO PC!!!)