MOSCOW -- Boris N. Strugatsky, a prolific writer who used the genre of science fiction to voice criticisms of Soviet life that would have been unthinkable in other literary forms, died on Monday in St. Petersburg. He was 79.
The cause was heart failure, Mr. Strugatsky's biographer, Boris L. Vishnevsky, said.
Employed as an astronomer at a state observatory, Mr. Strugatsky began collaborating on science fiction with his older brother, Arkady, in 1956. Together they produced rich and often bleak allegorical landscapes that ranged from a dysfunctional institute for the research of magic in "Mondays Begin on Saturday" to a postapocalyptic "zone" littered with deadly extraterrestrial objects in "Roadside Picnic," later adapted for Andrei Tarkovsky's revered 1979 film "Stalker."
That some of those worlds resembled the Soviet Union was not lost on Mr. Strugatsky's readers.
Though they were committed Communists, the Strugatsky brothers used their novels to express growing disillusionment with the Soviet Union after the 1968 invasion of Czechoslovakia and the end of a relative thaw in Soviet society.
In 1969, when the brothers finished the novel "Prisoners of Power" (also known as "Inhabited Island"), set in a galactic utopia recognizable to many as the Soviet Union, government censors told them to replace the Russian names with foreign ones, and they complied.
But Boris Strugatsky was celebrated less for his social criticism than for confronting his characters with philosophical quandaries that had no apparent answer. In one of the brothers' most famous novels, "Hard to Be a God," a time-traveling hero trapped in a despotic, violent medieval kingdom must decide whether to topple the monarch or let events run their course.
"Sooner or later, every character faces a choice, a moral dilemma," Mr. Vishnevsky, the author's biographer, said in an interview. "For my generation, these books were our upbringing. They taught us who we should aspire to be."
Boris Natanovich Strugatsky was born on April 15, 1933, in Leningrad, now St. Petersburg. Survivors include his wife, Adelaida, and a son, Andrei.
After his brother's death in 1991, Mr. Strugatsky wrote just two books, under the pen name S. Vititsky. He earned a reputation as a critic of the Kremlin under President Vladimir V. Putin, and exchanged letters with the jailed oil tycoon Mikhail B. Khodorkovsky, who had been a financial backer of opposition parties and an ardent foe of Mr. Putin's.
In a radio interview last year, Mr. Strugatsky spoke of his fear that Russia's ruling elite would "tire of playing at democracy."
"I, unfortunately, am a pessimist," he said in the interview, broadcast on the radio station Echo Moskvy. "I don't believe in anything good that involves a large mass of people. When the people are many, they are, as a rule, bad."
This article originally appeared in The New York Times.