User blog comment:JordanaBrewsterFAN/Mass Effect 3 4th DLC./@comment-1786741-20130122002039/@comment-24174486-20130123165754

Leviathan revealed a wealth of information about the galaxy before the rise of the Reapers and the creators of the Catalyst, information that wasn't revealed during Mass Effect 3 and that wasn't essential to ending the Reaper threat.

"it's impossible to have tension because we already know how the story will end."

Did most players know how Mass Effect 3 would end? Yes. Did most players know how Mass Effect 3: Leviathan would end? No. There's plenty of tension in how Shepard seeks out an ancient unknown entity, and with each step learns more about and draws closer to the Leviathan.

Omega was intended to be more action-focused than story-focused, and while it's light on the story, it provides the excellent synergy between Aria and Nyreen as well as the influence of Shepard's choices on Aria to compliment the simple plotline.