A beat-em-up game set in the X-Men Universe, X-Men Legends II changes the plot from X-Men Legends - whereas the first had the X-Men battling Magneto, the second introduces the villain Apocalypse and forces the two groups to team up against him.
The main improvements in the game are the new characters added. Because of the uniting of the X-Men and the Brotherhood of Mutants, the characters of both sides are accessible. Replacing Magneto as the villain is Apocalypse, and thus replacing the Brotherhood as the sub-villains are Apocalypse's various servants and the miscellaneous other villains of the series, such as Archangel, Omega Red, and Mr. Sinister. The underlings and low-level characters are represented by the denizens of whichever hostile environment you are in; for example, hostile bugs in the Savage Lands or soldiers in the prison camp.
Each mutant has their own set of powers based around their specialty. In some cases, these are simple attacks; Colossus, for example, tends to mostly have stronger melee attacks with few special effects. In contrast, Storm has a wide range of weather-based powers. These powers also find some use in puzzle parts of the game; Storm and Iceman can use their powers to put out fires, while Magneto can pull certain switches from a distance with his magnet powers. The powers tend to be pretty flexible, so you have a choice of people to use and aren't limited to a single character by fear of missing a solution.
The player in single-player mode controls a four-person party, whose members can be switched between using the D-Pad. In multiplayer mode, each player controls one mutant (if there aren't enough players, the remaining characters are AI-controlled). The AI works pretty well, and handles itself decently. It can be given simple commands - basically "stay close" when enemies aren't around and "attack my target" when they are. As for the player's character, depending on who you pick gameplay can either be a controlled environment with lots of strategic targeting or a close-quarters bash fest. There are alternate costumes available for each character, and plenty of unlockables to keep fans busy. Finally, there is a trivia machine in the base camp of each level that rewards the player with experience for answering X-Men related questions correctly.
The graphics are cel-shaded to look like a comic, which works nicely. They haven't aged well, however, and the textures don't look as good as they probably used to. The sound is all right, though they didn't get as many voice actors from the movies as they might have (Patrick Stewart does show up as Xavier, though).
X-Men Legends II takes what made the first game good and adds a whole bunch more to it. For the most part, this is a really good game.