Mortal Kombat: Deception is a 2004 fighting game developed and published by Midway. The sixth main installment in the Mortal Kombat franchise and sequel to Mortal Kombat: Deadly Alliance (2002), it was released for the PlayStation 2 (PS2) and Xbox in October 2004, the GameCube in March 2005, and for the PlayStation Portable (PSP) as Mortal Kombat: Unchained in November 2006. Following on from the events of Deadly Alliance, the game’s plot centers on the recently revived Dragon King Onaga, who upon defeating the Thunder God Raiden and sorcerers Quan Chi and Shang Tsung attempts to conquer various realms, meanwhile surviving warriors from prior MK titles join forces in a bid to stop him. In addition to online play and new chess and puzzle minigames, a revamped Konquest Mode from Deadly Alliance features a secondary plot line following the life of Shujinko, a warrior deceived by Onaga into finding artifacts to increase his power.

Designed by series co-creator Ed Boon, the game was created with the intent of surprising MK fans with new and returning content, as well as providing a more realistic combat experience in order to preserve the series signature gory violence. Several parts of the gameplay, such as combos and arenas, were redesigned to accommodate the new style of realism as well as be more interactive for players. In addition, the game was designed with the online play in mind, which had yet to be established into a fighting game.

Upon release, Deception was positively received by critics, who praised the reworked combat and plethora of new features, but criticized the revamped Konquest Mode due to its poor story and voice acting. The game managed to sell more than 1 million units by the end of 2005 and was nominated as the best fighting game of 2004 by several game publications. It has since been regarded as having been the first fighting game to incorporate online multiplayer, which later became an industry standard for the genre moving forward. A sequel to Deception, Mortal Kombat Armageddon, was released in 2006.