The game features new large-scale bosses, an online co-op mode and Trophy support.Unlike the first game, the SIXAXIS motion sensing of the PS3 controller was not used for “charging” the Ninpo magic, but instead utilized as a secret way to “jiggle” the breasts of female characters. While Sigma 2 has additional content not in the original Ninja Gaiden II a large amount of content was also removed from the game, or altered. With Team Mission Mode, the single player version is removed. Players instead are given a computer-controller partner (if without a second player or offline). In Story Mode, Karma Scoring is removed and now only done in Chapter Challenge. Tests of Valor were also removed, scattering the rewards across Ryu’s chapters. The total number of enemies in the game was reduced. Thus, fewer characters are on screen; enemy health was raised to compensate. Five new bosses were added, replacing two old boss encounters. There is one new boss for each alternate character’s chapter (including returning bosses from NG:DS and NG), a Dragon to replace the double Quetzalcoatl fight (though Quetzalcoatl can still be fought alone as in NGII), and two giant statues; a giant Buddha Statue, and a Statue of Liberty animated by Alexei. The Tunnel Worm was omitted, causing Ryu to fall through a tunnel leading from dark night to bright day. Most flying enemies were removed due to infinite ammo.
Source: Wikipedia, Game’s homepage
