After years of Marvel vs Street Fighter, Marvel vs Capcom, and the later Capcom vs SNK line of video games (not to mention crossover cameos between Soul Calibur and Tekken), it was inevitable that both Midway and DC would want in on the action. After all, each have had their own fighting game lines (Mortal Kombat and Justice League, respectively) and both have been routinely panned by critics in recent years. Since Capcom's not doing so hot right now, it would seem an ideal time for the MK line to step up and offer something entertaining to pull in some market share.
The resulting idea, of course, is to build up a storyline in some fashion that manages to get DC's heroes and villains and MK's heroes and villains all into one place, at one time, with ample reason to beat the stuffing out of each other. And despite the problems of the Mortal Kombat line in recent years, they've managed to get back to their basics and produce a pretty enjoyable title.