Prime Directive doesn't apply to non-federation species
So I was thinking, the game is set in an area of space that isn't under Federation jurisdiction, and non-Federation ships can do as they please (to the limits of what their culture allows). So I was thinking based on the of War on the Worlds, but instead of it being a radio drama, what if a Federation starship witnesses raiders, attacking a pre-warp species? If it is a non-starfleet vessel what possible options are available to the crew? If it is a Starfleet ship, due they have a duty to respond? Sit back and watch the attack? Hail and give a very stern statement of their disagreement and walk away?