StarCraft was a game that had surprising emotional power, given its somewhat detached in-game perspective. It was the active participation of the player in the unfolding events that made it work so well. When Arcturus Mengsk left Kerrigan to die at the hands of the Zerg, the sense of betrayal was so much stronger for having truly been the one who was betrayed along with Jim and Sarah. Then beginning the Zerg campaign, guilt as the contents of the 'chrysalis' I had been tasked to protect was revealed. Guilt and disgust for having helped to destroy a friend and create the "Queen of Blades."
Starcraft told us the story before the gameplay, completely separating both concepts. Blizzard's design team needed to tell a story with small animations inside little frames and text, simulating strategic communications between races. The result was a perfect excuse for the gameplay. Each mission had an excuse to be, not only "destroy your enemy" but dressed like "we need to conquer this area in order to avoid the Zerg arriving with reinforcements".
Ricardo Carretero, Tragnarion Studios