The goal of most, if not all, fighting games is to defeat the opponent before they defeat the you, the player. To win against the opponent a player must use a character to attack and deal damage to the enemy till their life or hit points reaches zero. So, how is this any different than Rock'em Sock'em Robots? By this description the game would sound very simple. Though the red and blue robots provide their own challenging entertainment within these simple boundaries, games like Soul Calibur, Tekken, or Mortal Kombat expand on the principle of fighting by providing more than one playable character with extensive and unique fighting styles.
This could be described as a growth in the rules to make the game more challenging or it could be the correlation of the real world to the fictional world. In the real world, people who have had martial arts training or the like are trained to not only dish out pain, but to read opponents and anticipate their movements. By doing so the martial artist can react accordingly to an attack and counter. I feel that fighting games today are trying to apply this aspect of fighting to get players to develop a sense of higher game play. In Soul Calibur V's case the characters have specific moves that vary in speed, power, and range. A veteran gamer can learn to use one or more characters, based on preference of character design or accessibility, and use their specific move set to their advantage above simply hitting the enemy. An example would be putting in an input at a key moment that makes your character artfully dodge an attack and simultaneously counter, thus giving you the advantage and a sense of achievement.
These fancy inputs can be categorized as fiction but are really rules. The relationship of the player and the fictional world is what provided the counter in the example. The player has to rely on critical thinking and reaction time to provide or to recognize openings and then use the mechanics to exploit them. Same can be said for combo experimentation. The characters' moves have been formatted to put certain attacks together, while other moves can be used in succession to deal even more damage. An example would be using a move that can force an enemy into the air. The player can then input a completely different move to follow up the initial attack to deal damage while the enemy can't retaliate.
Though the idea seems logical, there are issues with these rules. Some moves are limited and cannot be used in succession of one another. There are two main reasons why this is; The first is that designers didn't want players to be able to continually pound on opponents while in the air or on the ground and vice versa. The second reason is that the combat is a fictional world drawing from the real world. There are rules specifically made to hinder some attacks to make the gaming experience more like the physics of the real world and in turn more challenging.