Upon release, Ultimate Alliance 2 received mixed to positive reviews from critics, who generally found it to be inferior to its predecessor.

The rest of the story is derived from the consequences of those actions", stated Dan Tanguay, creative director for Vicarious Visions.

[6] The game then follows the Civil War story arc: a fight between heroes and villains causes an explosion in Stamford, Connecticut, killing 612 civilians (including a number of school children).

[9] Nick Fury leads a team of superheroes on an unsanctioned attack on Castle Doom in Latveria after discovering that the newly elected prime minister, Lucia von Bardas, has been supplying weapons to the Tinkerer, who in turn sells them to supervillains.

One year later, Von Bardas returns as a cyborg and joins forces with several villains to destroy New York City as revenge for the attack on Latveria.

The heroes defeat Von Bardas, but the destruction and Fury's unlawful actions cause the U.S. government to consider the Superhuman Registration Act (SRA).

In light of this incident, Fury disappears and Maria Hill is sworn in as the new Director of S.H.I.E.L.D., while Iron Man begins lobbying against the act in Washington, D.C. Three days later during a telecast of The New Warriors, Nitro kills over 600 civilians in Stamford, Connecticut, prompting the SRA's immediate passage.

The two sides have several skirmishes, including a Pro-Registration raid on a White Star base, and an Anti-Registration attack on a prison convoy carrying their allies.

When the Anti-Registration heroes respond to a hostage situation at a Stark Industries chemical plant, Iron Man appears and reveals it to have been a hoax.

To obtain a sample of the nanite formula, the group travels to Prison 42 in the Negative Zone, where most of the captured heroes and villains are held.

They collect the samples and Fury activates the prison's self-destruct system to prevent the nanites' spread but does not escape with the others; he and several other heroes are presumed dead.

A group of heroes travels to Wakanda, where they help Black Panther and the Dora Milaje defend the country from nanite agents, now under the moniker of "The Fold."

The heroes infiltrate a base in Iceland to broadcast a nanite stasis signal that will paralyze those in the Fold's control, allowing them to be cured.

At the culmination of their mission, the heroes face off against Tinkerer, revealed to be the Fold's creator, and a nanite-controlled Nick Fury enhanced with numerous superpowers.

On October 9, 2009, downloadable content was announced for the PlayStation 3 and Xbox 360 versions, which included new characters and comic missions,[19] as well as new achievements.

[26] Vicarious Visions, developers for the PlayStation 3 and Xbox 360 versions, upgraded the Alchemy engine[27] in several ways, including adding Havok physics technology,[6] a new 3D sound system[6] and syncing character's lips to dialogue.

[29] Users could follow Vicarious Visions' creative director Dan Tanguay and executive producer Jennifer Oneal on Twitter as they answer questions and post news about MUA2.

[32] n-Space created a series of articles to address fan concerns, the "perceived shortcoming[s]" of the game, and to answer questions.

(Broadcast Realtime Accomplishment Gloating), which allows players to share level results and high scores, and also features extensive use of the Wii remote for puzzles and manning turrets.

[39][38] Brian Michael Bendis, writer for Marvel Comics, was given an early opportunity to play the game, to which he later tweeted: "Happy to give a huge thumbs up for 'Ultimate Alliance 2.'

[44] 1Up.com's Thierry Nguyen was more critical, saying that the game was "like Ben Reilly: almost, but not quite as good as the original", citing issues with alternate costumes that "seem pretty lame", "a persistent feeling of oversimplification" and that a hope that "either Raven returns as the developer or Vicarious Visions learns from its missteps".

The game features a team of heroes uniting to prevent Thanos and the Black Order from obtaining the Infinity Stones.