softimage, we miss you…
Really interesting stuff! A lot of this could be easily applied within Blender, although some of it might take some more work. I appreciate how realtime-friendly it is (although I guess being a game that’s to be expected). Short render times are great for small studios or single animators.
What does this have to do with Softimage ? Guilty Gear is made with UE4 game engine as far as I know.
He mentions that they used Softimage specifically for its control over vertex normals, not sure if there’s any other particular relation there.
Totally agree. Really great technique. I love NPR and this one is really well done.
Motorsep@ about 10:00 they explain a bit why XSI (but probably, as ever, the real reason he is well versed and well know the software)
Unfortunately without a way to manually edit normals this technique is pretty far out of the reach of Blender (the custom outline shader part looks like it could be done soon though, it looks like custom vewport shaders are not so far out on the horizon for Blender)
After a little poking around it’s possible to store custom normals in a vertex color channel, and then apply them like a normal map with a node material, but it’s really difficult to work with since there’s no GUI for editing the normals.
Another reason why they still using softimage:
Agree, maybe in 2.76 or 2.77 we can have some surprise.
A few nifty tricks in here 
Actually one of the reasons people were so excited for Sebastian’s mesh-transfer patch is that it does allow for custom normal editing.(You basically make two versions of a mesh, one with proper geometry, and the other with better lit geometry, and have the latter’s normals transfer to the first.)
It’s not the same as actually manipulating the normals, but Blender should have some of the tricky mesh-data stuff done now. Now the tricky UI stuff would be the primary concern, so it could be an idea to ask on the irc/mailinglist if this type of stuff is on their radar and how you can help 
There is actually more tricks they did, like bizare camera trickery and having ‘frame animated smoke’ models and the like. But for a bunch of them I am honestly wondering the value.(Especially the bizar camera trickery)