User blog comment:Tribellium/Metal Gear Solid: Ground Zeroes Announced, With Sense of GTA-esque/@comment-1854594-20120904012132/@comment-1854594-20120905131749

So what exactly is your definition of sequel? Because to me a sequel is the continuation of the story and that's what Riptide is. It has all the original characters, just turns out they didn't live happily ever after and have to deal with the zombies again.