Games you can play for free – Delphi

Continuing with my project to create a list of great games you can play for free, this post features a unique game created by Martin Kruskal, where the objective is to guess the rules devised by one of the players.


Number of players: 3 – 7

Playing time: 30 minutes

You will need:

  • A standard deck of playing cards
  • Some chips

In each round, one player is designated as the ‘Oracle’; all other players take the role of ‘Followers’. At the start of the round, the Oracle decides upon and writes down (in secret) a rule that governs whether or not a card can be successfully played. The rule must relate to the card itself. For example the rule “if the previous card played was odd, the next card must be red” is acceptable , whereas the rule “cards can only be played if the minute hand of the clock is between 2 and 8” is not acceptable.

The deck of cards is shuffled and placed face down in the centre of the table before the top card is turned face up beside it. Thereafter, the Oracle turns over each of the cards in the deck one by one. After each card is turned face-up, all Followers must state whether they think that card adheres to the sequence decided by the Oracle. A good way for Followers to do this is with a card with ‘yes/no’ written on it. The ‘yes/no’ cards remain covered until all Followers have made a decision and placed their cards on the table. At this point, all cards are revealed, displaying either a yes or a no.

If the card turned face-up adheres to the Oracle’s rule, it is placed next to the previous card. If the card does not a adhere to the Oracle’s rule, it is placed above the last card to adhere to the rule. Therefore, a horizontal line will be formed from all correctly played cards with vertical lines protruding from these cards containing cards that were not correctly played.

Followers who were correct in determining whether or not the card would adhere to the rule are awarded one chip. Players who were incorrect lose one chip (note that a player cannot loose a chip if they do not have any; they simply stay on zero chips).

The round ends when all cards have been turned face-up and placed by the Oracle. Followers score points equal to the number of chips they own. The Oracle scores points equal to the maximum number of chips any one follower has minus the minimum number of chips any one follower has. I have used my own scoring system (as opposed to the official one) due to simplicity and so that it is in the Oracle’s interest for some (but not all) players to quickly deduce the rule. Ideally, a game of Delphi consists of a number or rounds equal to the number of players, ensuring everybody gets to be the Oracle. The player with the most points at the end of the game is the winner.


One thought on “Games you can play for free – Delphi

  1. Pingback: List of games you can play for free « Michael's Blog

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