THE WORLD'S A STAGE AND WE ARE PLAYERS
Often, games -- particularly digital games, with their use of video and audio -- are compared to film, probably because the videogame publishing industry strongly resembles the Hollywood studio system. But I don think this comparison is particularly constructive, in that it gives us little insight into what the game, as a form, is capable of. Film tells a static story; what exciting about the game is that it allows the audience to interact with a set of rules. This doesn't mean the game can't tell a story: in the role-playing genre, the players aren't merely watching a story but playing the roles of the characters within the story.
A better comparison than film is theater, which is where a lot of our game vocabulary ("the player," "stages," "set pieces," "scripting") comes from. A play defines the roles, events, and scenes of a story. An individual performance of those roles and scenes will always be different: different actors will perform the same role in different ways. Every performance and interpretation of a particular play is different -- sometimes in minute ways, sometimes in radical ways -- but we consider the play itself and the scene itself to be the same.
Compare this to a game story, particularly a videogame story. Every player will perform the story called Super Mario Bros. differently (and the same player will perform the story differently each play), but the role of Mario and the actions Mario is capable of taking remain the same. There is always a scene called "World 1-2," although each performance of "World 1-2" will be different. In a more contemporary videogame such as Half-Life 2, a very clearly cinema-inspired game, each player will always pass through the events the designers have scripted in the order in which they are presented, but each player (and each play's) performance of Gordon Freeman, the game protagonist, will be at least subtly different. The player will always get chased across the rooftops by cops, but in one performance she might hesitate, unsure of where to go, in one she might head straight for the escape route, in one she might panic, almost getting Gordon Freeman killed, and in another she might walk a little too close to the edge of the roof, fall, and have to start the scene over.
There is always a scene called "World 1-2," although each performance of "World 1-2" will be different.As game storytellers, we are not directing static stories take-by-take but rather arranging the scenes that will comprise the shape of our story. We can begin to think of the player as someone performing a role we've written rather than as an audience who experiences our story without any input as to its outcome. We allow room for improvisation, room for the player to make a role her own. The audience of a game can be more usefully compared to the audience for a play than the audience in the movie theater. In videogames, the audience is there, live, with the actors -- or as the actors -- experiencing a single performance that is unique, despite the story having been performed and continuing to be performed many times.
Some players record videos of their performances, either for documentation or for the purpose of
recording a specific achievement, such as reaching the game conclusion as quickly as possible -- what is usually called a "speed run" (YouTube has given lots of these videos a means of reaching an audience). That there an incentive to capture individual performances of a game testifies to the amount of variance there is within a game depending on who's playing it.
GAMES AND CHANCE
The board and card game traditions have also given a lot to digital games. What I think digital games have taken the most from board games and card games is the way they manage chance. Both contemporary designed games and older folk games have invented many systems for managing chance. The six-sided die, for example, allows for the random selection of six equally likely outcomes (and can then be further used to access other percentages and ratios; for example, three outcomes, each represented by two sides of the die, or eleven outcomes with different likelihoods represented by two rolls of the die, and so on.)
Card games themselves are designed as a system for managing chance and gradually revealing information. When all cards are in the deck, every card in the game has (as far as the player knows) an equal chance of being in any position. Once a card has come into play and been seen by the players, though, the players then know where it is and can use that information to make guesses about the remaining cards. Cards also allow players to manage the pace at which they reveal information: a player might have a hand of seven cards hidden from the other players, who don't know whether those cards have come into the game yet or not. Poker is a classic game of using limited knowledge of the cards in play to predict the positions of cards not yet in play. This is what makes Poker an elaborate game of bluffing. One player tries to see through the other "Poker face" because the decisions she'll make are based on what she can predict about the information the other player is concealing. Contemporary game designers have contrived even more rules to control the reveal of information.
Aside from hiding information, chance is frequently used to break symmetry. Having different starting conditions between players prevents both players from having the same set of ideal moves, and thus having the game become a stalemate. Having different, randomly selected values between one play and another, or having different game events happen at different, impossible-to-predict times (or not at all), means that each game will demand a different strategy, keeping play from becoming stagnant.
Franz-Benno Delonge and Thomas Ewert's board game Container, for example -- a game where players trade and transport commodities -- uses chance to ensure that all players do not value the commodities identically. At the start of the game, a number of cards are shuffled and randomly distributed, one to a player. These cards describe how valuable the different commodities are to the players who hold them, and each card values the commodities differently. The cards are also kept hidden until the end of the game, each card seen only by the player that holds it. Because each player is aware of the entire possible set of values on the cards he knows which cards are in the game, and which card she, and therefore not the others, possesses he can watch the other players decisions and make deductions about which players have which cards, and therefore which commodities are valuable to which players.
Computers have an innate capacity for manipulating chance. Though true randomness doesn't exist, computers handle numbers easily and are capable of generating reasonably unpredictable probabilities of any size on the fly. Every computer has access to an infinite number of monkeys rolling an infinite number of dice.
Why is this useful? Because, as we've discussed, games have a unique capacity for improvisation! Though each scene has the same shape -- Link battles a gang of Moblins -- each performance is different. So what if, in one performance, one of the Moblins comes from the left instead of the right? Digital games have the capacity to create variations on many subtle details in every play, keeping the experience from becoming stagnant.
The differences don have to be subtle, either. In Chris Klimas and Joel Haddock's online game, Where We Remain, for example, the player is a boy searching for a girl on an island patrolled by monsters that are intended to evoke characters from Greek mythology. The layout of the island -- what tools are hidden in which caves, what areas which monsters patrol, and in which cave the girl is hidden -- is different every time, decided by a random number generator. In effect, this randomness makes the characters and events of the game more archetypal because the emphasis is on the shape of the game -- the boy's search for the girl while monsters pursue him -- rather than on the details like what treasure is hidden where. Games have lots of room for improvisation, for every play of a game or scene to be unique, and digital games in particular have easy access to a great degree of chance.