Roadsise Picnic and The Snail on the Slope are IMO two of their best books (A. B. Strugatsky). I really liked others like Monday starts on Saturday or It's hard to be a God.

Sci Fi by Ursula k. Le Guin is also written from a very different perspective. Earthsea cycle, which is more fantasy, but unike any other. Also the book on the planet where people marry in quadruplets, The Planet of Exile, part of Hainish Cycle. Whole Hainish Cycle is awesome, Left Hand of Darkness, Rocannon's World.

I was hoping to see this one - I was just about to post before seeing your comment. It’s not a long book, but it definitely sticks with you.

The movie inspired by Roadside Picnic (Andrei Tarkovsky's Stalker) is one of my all-time favorites.

The Doomed City is also great. Tried to read Noon and it was too unfocused for me.

Exactly what I wanted to recommend. Their books progressed from idealistic communist propaganda to disillusioned analysis of totalitarianism, while still (mostly) being set in the same fictional universe.