BLC is a game currently that's still in an early closed beta stage. If you're a competitive gamer and you enjoyed any of the following, you probably will enjoy BLC:
Heroes of Newerth
World of Warcraft (specifically pvp)
Dota
League of Legends
However, the best way to describe the game would be if you rolled up all of these into one game and turned it into an FPS/fighter hybrid online experience. It's really tough to explain, so watch this video:
http://www.youtube.com/watch?v=TgLKeZnlk4E
then check out the website and sign up for beta
http://www.bloodlinechampions.com