The vampire Kain has been running around causing havoc since 1996, when he debuted in his first game on the original PlayStation. He was joined by his partner in crime and former lieutenant Raziel in 1999, and the rest was history.
Since then, the Legacy of Kain franchise has been building lore and accumulating fans, mostly due to its dark charm and solid set of games. But a true continuation hasn't happened since Defiance in 2003, so we're all waiting to see what the newly announced Nosgoth can do.
Sadly, it doesn't really seem add to the franchise in any noticeable way, but it's not a bad way to spend your time if you enjoy third-person shooters.