The Genius, by A Skymin’s Mind #5

Truth Detector

Used as Season 2 Final Game, Round 2.

Rules

There are two players. Each player prepares a 4-digit password and tries to hide it from his opponent. Then each player, in turn, can start asking questions to each other, which must be answered untruthfully. In other words, if you ask “How many times the digit 0 appears in your code?” and you receive a reply of 0, it means there exists the digit 0 in the code (because the reply is wrong). However, this reply cannot be an impossible reply (such as an answer of “5” for the above, considering that there are only 4 digits) or an unrelated/evasive reply (such as “I don’t know”). Additionally, questions must only be about the password. When giving a truth or any of the forbidden replies above, the penalty is revealing a digit not in the password.

When one thinks he knows the password of the other, he may use the turn to answer instead, guessing the password. If this is correct, he is the winner; if this is incorrect, the turn passes to the opponent.

As this is a Final Game, there are three items given:

• Starting Player: The person with this item may start asking question first.
• Truth Penalty Exemption: If a person accidentally answers the truth, using this item he may avoid the penalty once.
• Double Turn: This item may be used to give an additional turn, be it for asking or guessing.