The pack follows Commander Shepard (Mark Meer/Jennifer Hale) and the asari pirate queen Aria T'Loak (Carrie-Anne Moss) as they attempt to liberate the space station Omega from the anthropocentric terrorist group Cerberus.

In the Citadel, Shepard meets crime lord Aria T'Loak, who explains that a Cerberus invasion led by the Illusive Man's top strategist, Oleg Petrovsky, has forced her into exile from Omega.

The DLC pack is set within the Milky Way galaxy in 2186, during the midst of a galaxy-wide invasion by a highly advanced machine race of synthetic-organic starships known as the Reapers, and prior to Shepard leading Earth's final stand.

[1] The narrative for the DLC pack begins after Shepard speaks to Aria T'Loak at the Citadel space station's Purgatory nightclub, where she is depicted as plotting her revenge in exile.

[2] To access the DLC, the player must accept her request to help her retake Omega, which has been occupied and blockaded by Cerberus General Oleg Petrovsky's forces during the events of Mass Effect: Invasion.

[9] In a developer's post uploaded on BioWare's official blog, Condominas explained that Shepard "must make decisions based on Aria and Nyreen's knowledge of Omega while balancing their radically different points of view on how to go about liberating the station".

[13][14] GameSpot editor Kevin VanOrd criticized Omega's "shallow storytelling" which squander its potential, and compared the pack's self-contained nature unfavorably to Mass Effect 2's "wonderful add-ons, which were pleasantly inserted into the adventure at large".

You can't return to the space station, you gain no crew members or Normandy guests, and Aria is deposited back on the Citadel--a bizarre circumstance fully at odds with her character arc".

He asserted that the in-universe excuses given that Shepard must travel alone to Omega without the Normandy or its crew "serves no story purpose here" and that this line of reasoning "barely works in Arrival".

He commented that Omega "doesn't bring enough of that signature storytelling to the forefront", noting that while he "love pulling the right trigger to shoot dudes", he also enjoyed "using the same button to interrupt a cutscene even more".

[3] Daniel Starkey from Destructoid found Omega to be disappointing overall and its gunplay to be slightly mediocre, but commented "there are a few new enemies that are fun twists on creatures with which we are already familiar".

[15] The US edition of the Official Xbox Magazine commented that Omega has hints of some rich backstory, but called it a "limited, pricey thrill aimed only at the series' most devoted fans" given its negligible narrative impact on the main game.

[16] The UK edition of the Official Xbox Magazine gave a more favorable review, commenting that "small-scale stories are what Bioware does best" and that "long-term Mass Effect fans will appreciate this return visit" in spite of the pack's steep price.