True to its source material
Instead of following the designs of the sequels like Alien games usually do, Alien: Isolation is more in line with Ridley Scott's film. Which means the game world looks and feels very much like a 1970's vision of future. Creative Assembly got access to the original production material and faithfully recreated things in game. And as a result A:I has a very authentic atmosphere.
Everything down to the soundtrack and story elements are like in Alien. Even the skimpy panties can be found on Ripley when you look downwards after waking up from stasis at the start of the game. At least if you did not set field of vision higher than 85 degrees horizontal, that is. Apparently -- as I learned from PC Gaming Wiki I read before playing the game -- Ripley's legs disappear if FOV is set high enough.
Great PC port
The settings defaulted to maximum when I first launched the game, which resulted it going to a 4K resolution due to me having it set as the highest possible on the Nvidia control panel for the previous game I played. That was a bit too much in this title for my computer to handle. But after I lowered it to 1080p the game ran at stable 60 FPS for the rest of the game. I also turned off film grain, motion blur, depth of field, and chromatic aberration out of personal preference.
Keyboard and mouse controls are also sensible. You can keep your hand on the WASD keys for mini-games and the like instead of having to move to the arrow keys. I have played some lazy ports where that has not been the case. I do have to say that the interaction with doors and such is maybe too varied, though. I am not so sure pressing different mouse buttons and movement directions adds to immersion. A simple E command would be enough for me, no matter to which direction your character pulls a handle.
Genre-wise Alien: Isolation is of first person stealth survival horror kind. Staying unseen is quite challenging. You have to largely rely on audio cues to know where enemies are. You are not invisible while leaning like in Dishonored and motion tracker does not really give accurate locations (and you do not even get it from the start).
You do get quite a few different weapons and craftable gadgets over the game but most of the time avoiding direct confrontation is preferable to avoid attracting the alien that cannot be killed. My favorite parts were when I got to battle multiple androids at once. Knowing no xenomorph would show up probably made those moments so great.
While the Working Joe androids can definitely be creepy, the alien is indeed the true source of terror in this game. And it is much more observant than the human and android enemies. The alien has evidently pretty advanced behavior it follows and it can even learn from your playstyle, though I cannot really confirm the latter. In practice, the behavior results in the alien constantly sort of circling around your position. Even if it never finds you, it will keep following you around.
The xenomorph is not completely bug free with its movements, though. Once I had it get stuck in a doorway and I got to play rest of the mission without it. Well, almost, as there was then a cutscene after which I could not find where I was supposed to go and suffocated in smoke. After loading a save, the alien got unstuck. But it was nice to know the creature does not simply teleport around. I also had the alien and a human enemy get stuck inside each other once.
Could use more autosaving
A:I seems to do an auto-save very rarely. Apart from the last mission, I believe it might in fact only save for mission starts. Instead, you have to manually save the game at save points similarly to Dead Space. Quick saves probably would not work in a title like this but in my opinion the game could easily autosave after elevator rides and cutscenes without losing anything.
My thoughts in missions with the alien aggressively chasing me often revolved around where was the last save point and what do I need to replay if I die. By the end of game, one is likely to be too tired of the alien to even consider playing the bunch of DLC missions the game has. I started on Crew Expendable but quit after dying for the first time. I suppose the 24 hours I spent on beating the game on Hard was enough for me. The advice people are giving to buy only the base game is a very valid one.
Characters have no depth
One thing I did not really think about until reading the reception part of the game's Wikipedia article is how little depth the characters get. Even Ripley is left fairly undefined. She is upset about people getting hurt but that is where it ends. Her arms also seem bit too skinny for someone who does a lot of physical work.
Samuels's sole characteristic appeared to be his odd need to see Ripley get some closure. Which I guess sort of makes sense him being an android, maybe fascinated by humans. I actually knew what he was from the start -- from his Bishop-like looks, I guess, though he did then also mention how little sleep he requires later on the Torrens.
I wondered if it was supposed to be a secret and there would be a sudden revelation when he goes hostile like Ash in Alien. But then the marshal casually mentioned him being a synthetic and apparently Ripley knew of it too. So no surprises came from there and he remained friendly till his very end. However, he did bleed blood instead of the white liquid when I shot him in mission 5. That is kind of odd or maybe merely an oversight by the developers.