Here are my two cents; make campaigns/missions unpredictable for replay factor, and have campaigns/missions that work around the player's choices. If I play through the original freespace campaign, I know who is going to die, what ships will be attacking me , and how the game will end. However; if there was a chance that an enemy wolfpack is lurking around and has an X chance to jump in and hasn't been destroyed on previous missions, and my wing has just been pulverized, I might be a little more anxious. Or what if in the Freespace 2 campaign, I decided to defect to Admiral Bosch's fleet to fight for the NTF? A nightmare to fred and re-work, but this is a choice that has a lot more meaning than "save X ship, X ship returns in Y mission."