People are instinctively bound to their own experiences. When we read, watch, or play a game, it is natural to fit the experience into our frame of reference. Discussions of analogy in literature run rampant. It is the whole foundation of many literature classes (or at least it felt that way in when I took English in High School and suffered through the perpetual search for symbolism in everything we read). Even when authors don't pull directly from a specific historical event as in the examples above, they are often inspired by it and borrow or meld bits and pieces. Robert Jordan did this heavily in his "Wheel of Time" series where his Artur Paendrag shares a lot in common with King Arthur and Mat Cauthon's experiences are heavily built on mythology surrounding the Norse god Odin. Tolkien himself drew upon the Old English language when he wrote of the Riders of Rohan. Indeed, he was a linguist specializing in ancient Germanic languages and texts such as Beowulf. One could very easily fit the description of Theodin's hall into Beowulf. People also look for analogies in fantasy such as the commonly spoken claim that Tolkien's ring is like the A-bomb. This comparison Tolkien denied, and I believe him, but the mere fact that is has been suggested so often speaks of a deeper truth. When people read, watch, or play fantasy, they look for real life parallels. It is part of what gives fantasy its meaning. This leads to the final and, perhaps, most important reason.
Just as fantasy breaks the need for specific historical accuracy, it also allows for the simple joy of exploring the unknown bounds of creativity. That may include the envisioning of a new world, a peculiar culture, a menacing villain, or a strange species. This, one may argue, is where reality becomes irrelevant. Yet I would submit that the limitless potential of fantasy is still constrained by the need for immersion.
From a practical perspective, fantasy does not mean creative anarchy. If you look at the great novels, books, and games of the genre you will see that they all have ties to the familiar. This makes the created world real and allows it to be immersive. A three year old child can come up with a fantasy, but that doesn't mean it's a good one that an audience would be interested in. Theoretically, a designer could make a game where swordsmen duel with loaves of bread, archers shoot traffic cones, and merchants barter in maple leaves, but would there be a market for it? Probably not, and even if it were, it would be a cult following off the mainstream.
Almost all highly successful fantasies draw upon a measure of the familiar. This does not always happen to the same degree, of course, but the better the grounding, the stronger the fantasy usually ends up being. The goal of any movie, book, or game is immersion (that and making money, but that money is achieved through popularity which usually comes in part from successful immersion). The experience should gain a level of reality where the watcher, reader, or gamer accepts a measure of disbelief and accepts that what they are experiencing is "real." Anything which forces the participant out of this mindset has the potential to diminish the potency of the experience. Because of this goal of immersion, familiarity is important. We are much more willing to accept what we are familiar with. When something is odd, especially if it lacks internal consistency, we are less likely to be immersed. When we are not immersed, we are much less likely to enjoy the experience.
So what does that mean for games? Is the background history of Warcraft supposed to be analogous to some period of human history? Must the weaponry of WAR exactly match the technological levels of some specific date in real time? Of course not. Yet the world and its history must make sense. Most people don't have the skills and qualifications to make mighty statesmen, generals, or multi-millionaire CEOs, but we generally do have an idea of socio-political, military, and economic relationships and will know if something is off. Because of this all fantasy is still bound to some degree by reality.
I will close by using an example of the most "out-there" popular game I can think of off the top of my head. That is, the game Spore. I must add for clarification that I have not played Spore so if I am inaccurate in the specifics, forgive my errors. Yet detailed knowledge isn't necessary for the comparisons I wish to make here. Spore is, by its very nature, a cartoonish game rather than one aspiring to strict realism. Despite its cartoon ambiance, however, it does draw on reality for source material. First of all, the game's science is internally consistent. Secondly, it is tied (albeit loosely) in modern scientific concepts. Without the Theory of Evolution as a building point, this game never would have been inspired. From there, the Spore evolves into its tribal, civilization, and space expansion phases. None of these pull from specific real world events, but the concepts of tribalism, division of labor, currency, the development of tools, war, and diplomacy are all drawn from real concepts and use real societal evolution as their point of inspiration.
As much as we may like to think we can completely divorce ourselves from reality when we enter the fantasy and sci-fi genres, we cannot break the ties of our own experiences. Different fantasy games, books, and movies have varying levels of links to the real world, but none escape it completely. When those ties are considered, they must not only be internally consistent with the created-world but they must also be accurately pulled from reality. If this is not done, the risk is that the game, book, or movie may be off-balance, non-immersive, and therefore put off its target audience.
