Sigma and Black are very close. There are some nitpick differences. The major difference is they added a new playable character, Rachel. This was in the dark ages of DLC and remakes, so they stuck her into the middle of the game instead of an additional mode. And unfortunately it hurts the pacing, plus Rachel can be a little boring to play.
Ninja Gaiden Black is like Dark Souls before Dark Souls was a thing, so you can cut the sensitive fans some slack. Overall it’s fine, and I’m excited to play it. The Rachel levels will just be kind of annoying.
Sigma 2 has new side missions too, but they’re actually not so bad. Its problems go deeper. Sigma 2 is the infamous reworking of NG2 by new producer Hayashi after former director Itagaki left the company. Itagaki played up his rock star persona (documentary) and that’s reflected in the gameplay of NG2: hyper-aggressive, almost overwhelming, but get it right and there’s no better high.
There are a lot better lows, however, and that’s what Sigma 2 addressed. They reworked some awful boss fights, lessened some of the frustrating enemies, and eliminated some less useful throwing weapons. For the most part, these were smart, modern changes.
The problem is they also removed the essence of Ninja Gaiden 2. In that game, you fight hordes of difficult enemies and you’re challenged to improve your skills to defeat them. There’s nowhere to hide and no way to defend yourself indefinitely. You have to kill them faster than they kill you. At the highest difficulty level, this became total madness. It was certainly frustrating too as you sometimes exploded within seconds of restarting the checkpoint. The game may have been the peak of the videogame “bullshit” era before modern sensibilities took over (for good reason). But it also gave you tools to overcome the challenge, and when you abused the invincibility frames just right to slaughter a room full of ninjas, it felt amazing.
It also ran like total shit. The story goes that they ran out of time before they were able to fully optimize it. Or maybe that generation of console couldn’t handle it. Or maybe the PS3 especially couldn’t handle it. Or maybe Hayashi didn’t like bullshit. For whatever reason, he decided to drastically reduce the enemy count. Since you had the tools to cut down a horde of enemies, they had to adjust the difficulty in other ways. So they used fewer enemies but gave them a ton of hit points, and they made grab attacks do an extreme amount of damage. (Grab attacks happen to be complete bullshit, so what really changed?)
Now you weren’t getting juggled to death within seconds, but you weren’t hitting the same adrenaline rush either. You’re still playing a flawed game just like every other character action game. But without the highs, it misses the point.
Fortunately, playing Ryu in the sequel is still a lot of fun. I know I’ll have a blast. It’s just a bit of a letdown. There’s no other game like Ninja Gaiden 2, and now it might be lost in the dustbin of console history.