The ETO develops Three Body to recruit the lower classes, but the lower classes are alienated by it (Situational Irony)
In an attempt to make their cause more approachable to "the masses," the ETO (which is made up of mostly academics and scientists) develops the videogame Three Body. However, playing this game actually just confuses or bores working-class players, who are then further alienated from the ETO's cause. In this example of situational irony, the upper-class ETO members' attempts to become relatable further separate them from the people they're trying to recruit. (Liu Cixin actively denies that his works have any allegorical meaning, but perhaps there's some lesson in this story of wealthy elites creating a system that claims to appeal to the poor but actually just services other wealthy elites.)
Wang Miao is comforted by Da Shi (Situational Irony)
Wang Miao dislikes Shi Qiang at first sight. He finds the cop coarse, rude, and obnoxious; "he was exactly the sort of person Wang despised." Ironically, Da Shi's outlook and behavior—which Wang finds intolerable before his breakdown—are just what Wang needs in order to be comforted after his worldview shifts. When Wang is having a meltdown, Da Shi's completely different perspective saves his life. Wang's snap judgment of Da Shi isn't exactly wrong—Shi is coarse, rude, and obnoxious—but these things are shown to be ironically beneficial throughout the text.
Ye Wenjie's punishment/persecution puts her in the most powerful seat (Situational Irony)
As the daughter of professors and an academic herself, Ye Wenjie is made a political outsider during the Cultural Revolution. She's sent to a deforestation camp, where she and her fellow undesirables are essentially a wall of bodies between China and Russia; she's then brought to Red Coast Base with no status, only the hope of one day being "comrade." In an example of situational irony, Ye's punishment puts her in the perfect position to both send and receive Trisolaran messages. If she had been less persecuted at any point, she would have either no access or no motivation to send Earth's location to Trisolaris.
The three-body problem (Dramatic Irony)
While it might not be apparent to everyone who picks up the book, the title The Three-Body Problem gives away a large amount of information about the text. If the reader has an interest in orbital mechanics—or just likes googling book titles before reading—it's easy to realize exactly what Trisolaris's problem is, and the significance of the video game Three Body seems obvious. Dramatic irony (when a reader knows more than a character, creating tension) comes into play as we watch Wang Miao play multiple rounds of a game literally called Three Body without considering what we as readers know to be extremely important to the text: the three-body problem.
