Darque, there are no real conversations in Diablo. You couldn't intimidate, joke, lie, and have a genreal chit chat in Diablo. There was no real choices in how you interacted with NPCs. It ws either hack or not hack. Also how fast you took out the baddies were completely based on the player's speed of pressing the button. Nothing to do with character skill.
I can't comment of GTA: SA because I haven't played that game, and I doubt that I will.