Either one of Games Workshops two main settings, Warhammer or Warhammer 40.000
There has been a few RTS and FPS games (and an squad combat game called Chaos Gate) released so far. None of it too exciting.
*Daydreaming of what Obsidian could do with a setting where genocide, murder, rape, injustice, slavery, witch hunts, human sacrifice etc. are perfectly acceptable topics*