The base game was an amazing experience for me. It was like I'm a kid again and I just couldn't stop playing it till the very end. The story is a bit pretentious but interesting nonetheless, there are 2 endings and you might not realize which one is good. Shooting mechanic is the weakest point for that game, you either like it or couldn't stand it and at first I was ready to quit and never play it again (the tutorial with dodging monster attack is awfully bad designed) but after some time I started to like it very much.
The game is very moody, it's sad and mysterious. I think that game is perfect for a lonely weekend. The levels are gorgerous, I think it's the best photogrammetry usage I've ever seen in games. Almost everytime I caught myself on a thought that I don't want to leave the place which is strange, it's almost like the feeling of visiting the place from the childhood in a dream yet my environment different back in day. Perhaps it's some kind of nostalgia for something long gone from face of the earth. Designers for that old soviet lore did a fantastic job and I would personally kiss them for what they done.
DLCs are purely cosmetic and I strongly advise to not use them for the first playthrough. Music is quite depressive which is good, maybe that Zone Bard DLC is the only good exception to the above statement because after a while you'd want to change it on base, and you might spend a lot of time thinking what to build next.
There are several resources for building but for some strange reason you might be always short on mushrooms, so I'd recommend to plant those each day.
English voiceovers is quite good, Russian is almost fine except for the mysterious girl with green eyes, in some sequences I felt ashamed for the acting of that good lady.
There is also an RTX, good luck with that.
In my opinion it's could have been an AAA game given the proper funding. Gameplay wise it surpasses tenfold many other single player games I played as of late.