Fast, fluid, and a little flawed. Good improvements plus several thousand dead ninjas make it worth while.
So here we have Ninja Gaiden Sigma 2, the enhanced version of Ninja Gaiden 2. To be completely honest, there isn't a whole lot that changed since Sigma 1. The combat has been relatively untouched and there are a lot of returning enemies. You know what? Why change something that's not broken?
Sigma 2 does little in terms of gameplay changes but it does add a whole load of new content to play around with. Specifically weapons and moves you can perform. In Sigma 1, you can complete the game entirely with the Dragon Sword. Using other weapons, while plenty effective, just complicated things. In 2, I often found myself going long periods without using the Dragon Sword. In fact, the first time I found the Scythe I... well pretty much finished the game with that thing. There are several new (and returning) weapons that have additional moves and little bonuses that make the game feel fresh each time you use something different. They also improved the way the bow works, and while it does make things too easy sometimes, it still makes everything more fluid.
The enemies are less chaotic demons and more variations on ninjas. Personally, I think this is a good thing. The best parts of 1 was fighting the ninjas and other enemies that were as quick as you. I don't have a problem fighting big, slow demons once in awhile, but there were segments in the first that were just boring.
The frame rates and graphics are equally smooth and constantly impressive. I often wonder why Ninja Gaiden isn't praised for it's slick presentation. As far as action games go, it's one of the best looking.
The storyline isn't anything unpredictable. Might be a tad confusing to the few times the first game mentioned there being only 3-4 Greater Fiends. Then you go about killing all of them. And now in the second one there are 4 new and different ones. Storyline takes a backseat, understandably so, and the game is loosely tied together area to area. While not a problem, it does feel as though they sat around in a room and just came up with cool places to fight in. "I got it! A giant airship with robots and cyborgs! Who cares why the Black Spider Clan has something like that!". And in all honesty, who does care? The game is about fast paced, solid action, and that's what you get continuously. Although I will say, I found some areas and characters to be really memorable. Genshin, Volf and Elizabet are all characters that I found awesome and enjoyable to fight. The levels are usually really nicely designed, and one stage in particular where it's raining blood is just awesome for some reason.
Speaking of blood, the hyper violent tendency of the original Ninja Gaiden 2 (dismembering an enemy no longer results in rivers and rivers of blood) is lessened to a very noticeable degree. It isn't a game changer, nor something I'd dock it points for, but it is something worth mentioning.
The added levels with 3 new female characters are pretty interesting and surprisingly expand the story in a way I wasn't expecting. They're also equally as fast paced and fun as Ryu's levels, which again, after Rachel's levels in Sigma 1 I wasn't expecting that.
The camera still sucks. Ryu will disappear off screen once in awhile and you'll have to run in a circle for it to catch up and you can see what you're doing, exactly. Sometimes it will result in getting hit here and there, but it isn't anything completely difficult.
Ninja Gaiden's notorious difficulty isn't at full play here. Although that might be because of my Sigma 1 addiction... but still, I found the story to be rather easy, only dying a few times. Most casual gamers will find it tough, but the thrill to run on walls and be a speedy ninja is still awesome enough.
I will admit this review and my rating is a little bias. I find the entire world and Ryu, Ayane, and the rest of the characters to be really cool and slickly presented. One of my favorite action games, easily, and once you have the missions unlocked it becomes very "pick up and play". Downright fun and enjoyable. Killing ninjas (and robots... and werewolves... and dragons) has never been so awesome.