The Doomed City

The Doomed City (Russian: "Град обречённый") is one of the last novels written by the Strugatsky Brothers.

Set in a city where mysterious Mentors run a sociological Experiment. The City is filled with volunteers from various places and times, yet all can effortlessly communicate with each other. Apparently, the experiment runs out of control, the City is shaken by a social unrest and an egalitarian system of job assignments is replaced by a dictatorship. The leader of the new regime sends the main character to explore the bordering desert that limits their expansion. He is told to search for another city that the leader sees as a threat, despite having no evidence it exists. The expedition proves difficult in the extreme. One by one, the members turn back or perish. Only the hero Andrei and his friend remain. They pass the Crystal Palace, a briefly mentioned place that contains everything man desires, but still proceed, pondering their strange world and the meaning of human existence.

Tropes used in The Doomed City include:

Gainax Ending: In the end, after getting shot, Andrei is back in our world's actual reality in Leningrad, in his mother's apartment, shortly before dinner - and apparently he wasn't gone at all, to her. That means that it was either a dream or hallucination during the span of a few minutes, OR an instantaneous trip to a parallel universe OR an example of time travel, having been sent back by the Advisors after the experiment, OR he's still in the experiment and "actual reality" is only a hallucination, OR... seriously, what is going on? We are only told, via Andrei's Mentor, that he has passed the "first circle" but that "there are many of them ahead".
Mind Screw: Oh boy. While most of the rest of the Strugatsky's body of work is rather hard social science fiction, this is a heavily psychological surrealist mystery, full of symbolism, things that are heavily implied, but NEVER explained and, once you get to the last two acts (the expedition to the North and its aftermath), some extremely weird stuff. Not to mention the Gainax Ending (see above).
My God, What Have I Done?
A Nazi by Any Other Name: Party of Radical Revival
- Not quite. The leader is indeed a former Nazi officer, but he is sane, and the regime is milder than the Third Reich.
Ontological Mystery