Radical, like for example criticizing the party or leaders, would have landed you in prison/on death row.
More subtle creations, where criticizing is expressed via proxy of science fiction or abstract ideas would have never published, because every publisher and government censors would look at every sentence in your book as potentially having another meaning - critical of the party/leaders.
That’s when you would have to go full P2P blockchain with SAMIZDAT [1], manually typing copies of your text (using many layers of carbon paper) and distributing them in underground communities of intellectuals, hand-to-hand.
But if your unbaised view on USSR party/leaders/direction/methods was aligned with the party, then all newspapers, all book shelfs and book awards were yours to take.
Another artifact of the USSR is a mandatory line in your CV and references - that you were never involved in any anti-USSR meetings, protests and movements.