Do we actually have free will? Who determines this? Are we controlled by what we see and what we hear, even while believing we decide freely? Insider is a game that looks at these questions. While communicating to others, you have to find the correct answers to a quiz or find the "insider" who is manipulating the discussion. The insider will do everything they can to hide their identity while misleading the others.

In detail, players are assigned roles at random. One player will be the "master", and they secretly select a word from a set given in a deck of cards. (In a variant described in the rulebook, they can freely select and write down a word.) The "insider" player, whose role is not known to the other players, will then view the word secretly. The remainder of the players are known as "commons". The commons then have roughly five minutes in which to ask the master "yes" or "no"-type questions so that they can deduce the secret word. The insider tries to secretly lead the commons towards the correct word. If the commons fail to guess the word correctly, everyone loses.

However, if the word is correctly guessed in the allowable time, the master flips the sand timer, and the commons and master will have until the sand runs out to discuss the game and deduce the identity of the insider. If they guess correctly, they will win the game together; if they do not, the insider wins.