The goal of "Insider" is a battle of wits and deduction where players try to guess a secret word within a time limit. Meanwhile, they must also identify the Insider, a player who knows the word and is trying to guide the group to the correct answer without being detected.

The objective varies depending on the player's role: the Master provides clues, the Insider subtly assists in guessing the word, and the other players focus on guessing the word and finding the Insider.