Short Version: Horizon Zero Dawn is a magnificent open world game. Stunning visuals, amazing soundtrack and voice acting, variable game play, and an interesting story that keeps you guessing till the end, make this a must play game. Though some areas could have been improved, I'm looking at this in retrospect, from a PC point of view. Overall: 10/10

Edit: Finished New Game+ on Ultra Hard. Worth it. Challenge level increased quite a bit. Barely finished the final boss. 15 seconds to go. Wow. Worth every penny.
Original Playthrough: 98 Hours
Ultra Hard put me at 120

Story: Horizon Zero Dawn gives a compelling story that introduces a world that we could have imagined, but didn't. This story is something new. If you don't know anything about the story, please don't ruin it for yourself. You'll have Ah-Ha! moments, many times. You'll see realistic interpretations of life in a new setting. Heroes and Villains. Overall the story complexity is a solid 9 out of 10.

World: The world is very nicely fabricated with a lot of attention to detail. There are few areas that you're prohibited from going and even when you do reach one of those areas, typically the game warns you first, then sends you back. The only real issue I had was once falling through the wall and getting stuck, which you can fast travel out of and occasionally random resource spawns couldn't be interacted with. The terrain is varied enough to keep things interesting. One thing that struck me specifically was while the weather and time effects didn't have much of a 'game play' effect, they made me feel as if I was really in the real world. The sun effects and obscurity from weather, were amazing. 10/10.

Audio: This game honestly stunned me. So many times I just turn off the sound because it's boring. This was one of the few games I've kept it on, and didn't replace it with something else. The voice actors put some work into it with some well known names you'll recognize. Further, the music kept you in the zone and added tension at the right points and was relaxing at others. Aloy's commentary was a nice feature I enjoyed a lot actualy. The only negative was that eventually you hear all the same things you've heard before. I wish there had been a couple dozen more recorded variations. 10/10

Visuals: For it's time, this is a great game. Though compared to modern standards there are better things out there, this is still a beautiful game. I played this only on a 1070 and I wish I could have seen it at higher rez. There was a lot of attention to detail even at the lower quality settings. Some of this overlaps with the world review I've given before. For now though, I'd give it a 8/10.

Gameplay: This is where the game shines. As you learn and evolve with the game, you get better at using some of the toys they give you. Some toys I didn't like at all, however, there were tutorials for all of them. They are completely optional, but give rewards if you engage in them. The game allows you to do as much of the side quests or as few as you want. 100%ing the game was definitely worth it though, including The Frozen Wilds. Though I originally played on Normal, I'm going back to play on Ultra Hard for the final two achievements. Occasionally Aloy would move the wrong way depending on the camera view, but otherwise typically there weren't any strange issues. 9/10

Overall: This game is more than the sum of its parts. Though some sections I gave a lower score, overall it really does deserve a 10/10 rating. I don't often give that. However, I really did enjoy every hour I've poured into this game. I'm excited to play Forbidden West and see where Aloy's story goes after this as well as some of the unresolved threads that are promised to be picked up in the sequel. Glad this came to PC and glad I finally picked it up. This game deserves your attention if you haven't given it yet.