X-Men: Next Dimension
Narrated by Patrick Stewart (reprising his role as Professor Charles Xavier from the X-Men films), the game's plot is built around the Prime Sentinels retrieving the head of Bastion, and Bastion's subsequent attempt to wipe out mutant-kind. The game opens with the Prime Sentinels freeing Bastion from S.H.I.E.L.D. imprisonment, and then disguising themselves and selling the defense plans of Professor Xavier's School for Gifted Youngsters to the Brotherhood—the training grounds and home of the X-Men. The game then moves forward to Forge fighting off Mystique and Nightcrawler in a city ravaged by a Prime Sentinel invasion. The graves of Anthony Stark, Warren Worthington III, Peter Parker, and Benjamin Grimm can be seen in the background. This is revealed to be a Danger Room simulation, and the X-Men begin training their adaptivity by fighting opponents who have a tactical advantage.
During this training session, Juggernaut, and the Brotherhood of Mutants (consisting of Mystique, Toad, and Sabretooth) make their assault on the mansion. Xavier is curious as to the nature of their attack, worrying that it seems "too focused, almost like a distraction," and sends Forge to investigate the grounds. He discovers that the attack was a distraction, and that the grounds are now being patrolled by Prime Sentinels.
After attempting to fight off the Sentinels, Forge is abducted and the Brotherhood retreats. Restrained in the company of Bastion, the seemingly human Sentinel tells Forge he intends to use the man's mutant gift to bring about the extinction of mutants. He steals various weapon designs from Forge's mind, including a powerful weapon capable of stripping a mutant of their powers. In an attempt to throw the X-Men off his scent, He sends the Brotherhood to different locations across the world. The X-Men split up and engage each member in a bid to find Forge and stop the Prime Sentinel. After their defeat, the Brotherhood retreats to find Magneto in the Savage Land, only to find that Magneto has been hunted down by the Sentinels as well and is no longer in control of his fortress. The X-Men, having followed the Brotherhood, also arrive and Magneto charges the Brotherhood to fight them off long enough to convince them to join forces.
With the X-Men and the Brotherhood forming a temporary alliance, the team fights their way through a legion of Sentinels, though not without losses of their own. In the end, Magneto, Wolverine, Juggernaut and Phoenix invade the tower for the final battle with Bastion. Bastion uses Magneto's trans-mat system to transport Juggernaut away from the tower, then escapes to Asteroid M, but he is followed by a piggybacking Wolverine. Wolverine, whose healing factor was disabled by the Sentinels earlier, manages to defeat Bastion. Magneto and Phoenix arrive to help Wolverine, and Magneto prevents a weakened Bastion from escaping again. The two battle, and Magneto is defeated.
When Bastion returns to the central room, he finds Phoenix, who challenges and finally defeats him. The Prime Sentinels are disbanded, and the X-Men and the Brotherhood agree to a temporary cease-fire while the wounded are restored to health. Forge is freed and reverses the effects of his weapon, restoring everything to normal. With Bastion returned to S.H.I.E.L.D., the X-Men are free to continue training to fight for a better future.
Upon reaching the ending level of Asteroid M, the player has the chance to fight Bastion as three characters: Wolverine, then Magneto, and finally Phoenix. Whether Wolverine defeats Bastion or is defeated himself, the game proceeds to Magneto's fight with Bastion. If Magneto defeats Bastion, the finale video is simply accelerated and Phoenix does not fight Bastion. If Magneto is defeated, Bastion and Phoenix comprise the final fight of the game.
Alternate endings:
As Phoenix prepares to finish Bastion, Cyclops appears to help Phoenix. However, while they are both distracted, Bastion kills Cyclops by blasting him and leaves his lifeless body floating in space. Distraught over her husband's death, Phoenix transforms into Dark Phoenix and unleashes her fury on Bastion. Professor X detects Dark Phoenix's presence and is knocked over when Dark Phoenix destroys Asteroid M, also killing Wolverine and Magneto in the process. As Dark Phoenix flies through space, she destroys the Moon, and then turns to (presumably) destroy the Earth as well.
Juggernaut is revealed to be alive and well, but is trapped on Mars. As he is tossing a rock, it lands on his head, to which he replies "This sucks!".
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