Take the example of the narrative story in chess: it doesn't exist. The pieces do have a framing image to them, which is of two kingdoms at war. The names of the pieces bear the brunt of the work here - knight, king, queen, pawn, bishop, and rook (roughly translates to "chariot"). The mechanics are only somewhat appropriate to their pieces:
- The pawn is small and weak, and can only move one square at a time. They usually represent infantry.
- The queen rules over the land, being the most powerful.
- The king is powerful, but must be protected at all costs - he is not allowed to ride out into battle.
- Why does the bishop move diagonal and the rook move vertical/horizontal? Is there a flavor reason for this to be the case? Why does the knight have his L-maneuver?
So we can say from these observations that chess is both "abstract" in its ruleset, and that the ruleset is "narrative independent". Basically, the ruleset doesn't map onto reality, and the game doesn't require a narrative - the flavor is only there to give people something more natural to call them other than Piece 1, Piece 2, etc.
Compare this to a game like Call of Duty (a first person shooter, for those not familiar). The game takes place in World War 2, following a campaign across Europe. The basic mechanics of the game are shooting, moving, and avoiding being shot at. Some of it contains what we call "emergent gameplay" (which chess also has) - mechanics that arise out of the interaction of other mechanics and parts of the rules.
The rules in Call of Duty map closely to reality ... unless it would make the game less fun. When a player gets shot, they aren't taken out of the action immediately, and the bullet doesn't cause location specific injuries which affect gameplay. Getting shot doesn't really affect gameplay at all, unless your health drops below zero. There are a number of reasons for this - it would make getting shot frustrating for the player, it would make recklessness, a less viable option, and it would overall make the game less fun. The soldiers also don't have to worry about supply lines, eating, fresh water, infection, sleep, or any of the other major considerations of staging a war, because they would all make the game less fun.
So using the same criteria we applied to chess, we would say that Call of Duty is mostly "concrete" in its ruleset, and that its ruleset maps heavily onto its narrative. Though we could reskin Call of Duty with science fiction / fantasty, it best mapping is the one that the game is designed around. One thing we've seen though is that a certain level of abstraction and cheating reality is needed for a fun game. This is one of the problems with narrative in games.
The other big ones are a lack of sophistication in artificial intelligence (AI) and the branching problem.
The AI problem is that computers are still fairly dumb, even when they're smart. A single instance of AI doing something idiotic can shatter suspension of disbelief. The branching problem is that when they player is given high levels of interactivity, they expect to be able to do unexpected things. These problems are related.
In games like Call of Duty, the player's character (PC) might have one of four modes of speech.
- The PC says nothing, and is merely talked to. This option is used because players don't like having words put in their mouth, especially when they're otherwise in control of the PC.
- The PC says completely prescripted things. This option is used when a story needs to be told that involves the PCs discussion - not ideal for the above reason.
- The PC says something chosen from a list provided to the player. It gives interaction, but can sometimes feel restricting. It also allows the player to make a variety of moral choices.
- The PC directly uses the players voice. This option isn't used because there's no AI on the planet that can respond to the variety of things a player might say. Yet.
- One inevitable thing happens. Then another inevitable thing happens. This continues until the game is over.
- Same as above.
- One things happens. Then the player makes a choice of two or three other things to happen. Then the player makes another choice of two of three things to happen. This continues until the game is over.
- The player does things until he meets his goal (if there is one) by any means he chooses. Usually not possible.
This is one of the other reasons for abstracting the rules - programming all those things would not only make the game less fun, it would also be incredibly difficult and not offer a good return on programming dollar investment. There are very few people who would like to write letters to their sweetheart back home in a war game, so programming it in would be a waste of time. The only way to allow things like that is to make the game engine generalizable - which costs less money per fringe case, but still takes a lot of money and runtime computing power to do.
Because only a few options are available to players, games usually don't have much of a narrative. The narrative serves only as flavor, and to give instructions. The real value of most games is in the gameplay, not in the story behind the game.