guessing game
US /ˈɡes.ɪŋ ˌɡeɪm/
UK /ˈɡes.ɪŋ ˌɡeɪm/

1.
a game in which players try to guess something, such as a word, a number, or a person's identity, based on clues or limited information
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We played a guessing game where one person thought of an animal and others asked yes/no questions.
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The host led a fun guessing game with riddles for the party guests.
2.
a situation where it is difficult to know what will happen or what someone will do, often because information is being withheld or is uncertain
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Negotiating the new contract is a real guessing game because we don't know their budget.
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The stock market can often feel like a guessing game for new investors.