The game takes place after Raiden, Earthrealm's god of thunder, and Superman, protector of Earth, repel invasions from both their worlds. An attack by both Raiden and Superman simultaneously in their separate universes causes the merging of the Mortal Kombat and DC villains, Shao Kahn and Darkseid, resulting in the creation of Dark Kahn, whose mere existence causes the two universes to begin merging; if allowed to continue, it would result in the destruction of both. Characters from both universes begin to fluctuate in power, becoming stronger or weaker. Mortal Kombat vs. DC Universe was developed using Epic Games' Unreal Engine 3 and is available for the PlayStation 3 and Xbox 360 platforms. It is the first Mortal Kombat title developed solely for seventh generation video game consoles. Most reviewers agreed that Mortal Kombat vs. DC Universe was entertaining and made good use of its DC Universe license, but the game's lack of unlockable features as opposed to past installments of Mortal Kombat and toned-down finishing moves garnered some criticism.