Prophesies usually come in two flavors: a hero will rise to defeat the evil whatever or a great evil will arise to consume us all. Most of the time though, they're simply used to add an illusion of gravitas to an otherwise typical situation.
It has been foretold that in the future that when the world needs them most writers of video games will discover the most precious truth of all: putting prophecies in your game is lazy, weak storytelling. But for today at least, this terrible scourge of a tired, worn out trope continues to plague even our most popular, well reviewed games, even hardcore science fiction games that should be above such derivative mush. Yes, I'm looking at you Starcraft 2.
Before I lambast the otherwise solid Starcraft 2 for its laziness, let me lay out the case against prophecy. Prophesies usually come in two flavors: a hero will rise to defeat the evil whatever or a great evil will arise to consume us all. They usually come from one of two sources, an ancient civilzation now long disappeared that has left behind artifacts/codes/bas-reliefs that outline the prophecy or some lone prophet that no one is listening to until it's too late. Obviously there are exceptions, but most games that I can think of fit into one or the other of these models. The problem with all of these cliches is that most of the time they're simply used to add an illusion of gravitas to an otherwise typical situation. The world will end if the heroes fail. How do we know? Because of the prophecy. Oh, and only one person, the chosen one, can do it.
This stinks because it's so trite. It also stinks because it takes up space in a story that could be used for something more interesting, something that would give the hero actual agency in the story. There are tons of ways to show that a threat is looming without resorting to solemn proclamations of ancient doomsayers. Often the game is halfway there, with heroes and villains racing to find pieces of the ancient whatchacallit (as in Starcraft 2). But really nine times out of 10 it would behoove the writers to make the race about the characters and their insights, as any good mystery or spy story exemplifies.
When the Protoss super-guy Zeratul confronts the Queen of Blades during a protracted cut-scene in Starcraft 2, I was groaning my way through it, despite the stunning visuals. Blizzard spent a lot of time and money on this game and this scene, and I'm dumfounded that they would constantly resort to such battle-worn cliches. The two aliens exchange overwrought chunks of exposition and bland posturing, haggling like deluded priests over the meaning of some scrap of scripture. It was all assumed weightiness, none of it earned. The prophecy was just a shortcut.
And here's the best part. Prophecy would be lame enough, but few storytellers ever have the guts to just go with predestination. (And why would they? It's seldom very surprising.). So we get Zeratul's ridiculous pronouncement that "The prophecy is uncertain. There is always hope." Thus, the prophecy may or may not be true. Something awful might or might not happen. Thanks, Wise Old Ancients, very helpful!
The best use of prophecy that I've ever seen was in a TV show. I won't give it away for fear of spoiling it and because I'm not sure I remember it exactly right. I am sure that the way that I remember it, it was awesome, so that's what I'm going to recount here. The main character was driven by this prophecy, an ancient text that motivated him to do all kinds of brave things episode after episode. But then it turned out that the prophecy was a fake -- some villain had gone back in time (or wherever) and faked this prophecy just so the hero would be motivated to do certain things. That's how you use a prophecy -- by not using it to tell the future at all, but instead using it to tell an innovative story.