good info from developers:
New playable characters we say? Yes, brand new and even sexier (this is Team Ninja we're talking about). Sigma 2 will feature new playable female characters, which should be familiar to fans of the series and of Tecmo's Dead or Alive. The first is Ayane, the purple-haired ninja from DOA, who will come packing her own unique moves, weapons, magical attacks, and provocatively placed butterfly accessory. The second new character is Momiji, last seen at a lower resolution in Ninja Gaiden Dragon Sword on the DS, who will bring her own arsenal of abilities and weapons to the fray. Both characters will be integrated into the story, which will branch off to follow their adventures. Not to be outdone in the new content department, Hayabusa will face off against new enemies and bosses with some new weapons tossed in to help deal with the new foes.
Beyond new playable characters, Sigma 2 will feature an all-new online co-op mode that lets you and a friend team up to work your way through more than 30 challenge stages, which can be played in one of four difficulty settings. Your performance will be ranked and uploaded to leaderboards so you can see how you stack up against the world. The stages will be a mix of original areas and those seen in the single-player game, which are being redone for co-op play. Finally, the game will see a good amount of work put into refining the gameplay experience. The game's camera is being tweaked based on user feedback. You will also get additional cues on where to go next from your playable character because your character's head will look off in the direction you're supposed to go in. You'll also find a variety of additional tweaks peppered throughout the gameplay to help make Sigma 2 a smoother, sleeker evolution of its 360 counterpart.
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