If you are a fan of survival horror games and you haven't played this yet, drop everything and get this game IMMEDIATELY.
It's challenging in all the right ways, it's innovative in its resource/leveling system. All aspects of the gameplay are infused with the story and setting. It's one of the most cohesive and rewarding game experiences of all time.
Nothing shows this better than the map itself. Talos1 is a 1:1 completely fleshed out Space Station/Research Facility and by the end of your playthrough you will begin to see it's grand design and understand it's genius as every area is meticulously placed both inside and outside of the station. Most areas have airlocks that allow you to fly around the station and jump the different locations (some through hull breaches in the stations walls). There is also a grand lift that shoots through the middle taking you to the three main hubs. Then there is the G. U. T. S that allows you to float through the maintenance tunnels of the station and get around that way. It's so creative and well thought out and each zone has its own story and they almost all intermingle in some way.
Which brings me to another point, the story is DENSE. Specifically the world building and the personal stories of everyone in the ship's crew. More than any other game I've played the creators spend an incredible attention to detail compared to other games of this genre. When you see a dead body in a hallway or stuffed behind a maintenance shaft, they have names, and usually a specific story as to what they were doing before everything went to hell and how they ended up there; to the point that you can literally look up EVERY crew member of Talos1 by the various security terminals in each zone. This game is DETAILED.
So go do yourself a favor and pick up this game and enjoy not wanting to play anything else for the next month or so.