Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. In computational complexity theory, the Unique Games Conjecture is a conjecture made by Subhash Khot in 2002. The conjecture postulates the NP-hardness of the problem of determining the value of a certain type of game known as a unique game. It has applications in the theory of hardness of approximation. The unique games conjecture can be stated in a number of equivalent ways. The following formulation of the unique games conjecture is often used in hardness of approximation. The conjecture postulates the NP-hardness of the following promise problem known as label cover with unique constraints.