When Famitsu sent word of Ninja Gaiden Sigma 2's existence, we thought it would be a simple port of the Xbox 360 sequel with a few additional bells and whistles. Team Ninja slashed (see what we did there?) those thoughts and have revealed that Sigma 2 will include a large chunk of content, including two new playable characters and online cooperative play.

Team Ninja fans will immediately recognize the two playable additions noted in a Gamespot preview: Dead or Alive's purple-haired ninja, Ayane, and Ninja Gaiden Dragon Sword's female warrior, Momiji. Each character's tale will be woven into the existing Ninja Gaiden 2 story and branch off at certain points. That's all well and good but the freshly announced online co-op is what has our interest piqued. Unfortunately, the co-op skips the main campaign and offers 30 challenge areas that are playable on four difficulty settings (presumably, Ninja Dog to ZOMGWTHBBQ!). Still, it's a surprising (and welcome) addition to what could have ostensibly been considered a simple re-release.

And for those who prefer the simpler additions, Tecmo says they're in there too. New enemies, weapons, and tweaks to the camera and gameplay are all included. Ninja Gaiden Sigma 2 is set to land on the PlayStation 3 this fall -- the trailer is embedded after the break.

This article was originally published on Joystiq.