Bladestorm: Nightmare is a compilation of Bladestorm: The Hundred Years War from 2007, as well as a new alternate campaign mode with a dark fantasy setting known as Nightmare. Unfortunately, I didn't find either to be very compelling.
Omega Force is well known for the long-running Dynasty Warriors franchise and Bladestorm's gameplay is largely inspired by it. Warriors games are numerous and unique enough that they're practically their own genre, and like other 'niche' genres and franchises, they're fairly polarizing. Yet, they clearly have at least a strong enough following to generate new entries year after year. Generally speaking, I tend to gravitate away from the Warriors games, but given the chance, I wanted to give Bladestorm: Nightmare a go, especially given the Nightmare campaign and its dark fantasy elements.