Not a 30+ year war like in Halo for sure, but longer than a three day war most likely. Some things we do know:

- The conflict took long enough that people in Russia were able to pack up and drive in mass to the Cosmodrome seeking escape on a colony ship.There are a lot of cars, especially as seen in the 2013 E3 demo. So we can expect that these people at least had a warning that something bad was coming.

- That some of Humanity did in fact escape The Darkness to end up building The Reef somewhere in our solar system (like in the asteroid belt) suggest that the forces arrayed against Humanity weren't 100% all powerful as the Covenant generally were in space engagements where they often overcame humanity's superior numbers.

- There's the quote from the Grimoire: "Ask yourself: what threatened your Golden Age ancestors so much that they constructed the Exos to defend themselves?" Exos, as we're finding out, are really really advanced. To the point of being fully intelligent and having lifespans that stretch back to the Golden Age some hundreds of years ago. We're looking at a minimum of years of design for them I'd think.

With so little information it's hard to make an educated guess, but I'd think the war lasted a few years but less than a decade. Long enough for there to be Golden Age Warminds and weapons (the legendary guns we'll use are said to be from our Golden age) and Exos. I do think that once whatever defenses we had were finally broken through things went quickly from there. The miles of burnt out cars in Old Russia suggest something like a nuke that killed a lot of people in the same way at the same time, for instance.

I'm gonna have to pick up that book today :)

Is it a fantasy? (I guess I can look it up on Wikipedia but then that wouldn't be any fun).

I don't think we have any evidence the Traveler did much of anything. I don't even know if the Traveler lives inside the big ball in the sky or if he IS the sphere in the sky.

I am looking forward to some DESTINY fiction of some sorts, whether graphic novels or book novels.

3. In the Golden Age we had already built Warminds. We already had solar system patrols ready to engage enemies. I don't see the Golden Age as an age of militarization but its clear it also wasn't a Star Trek utopia. The interesting question is why have these things? The Traveler is said to have shared knowledge with Humanity. Could it have told us of the Darkness?

Do we have any evidence that the Traveller actually spoke with Humanity? Perhaps we learned technologies from the Traveller simply by the fact that the Traveller existed or from creations of the Traveller like the Ghosts? In which case we couldn't have known about the darkness until it was too late.

Yes. Bungie has said a few times that it shared information with us. I don't have any direct links or quotes at hand unfortunately, but the implication seemed to be that The Traveler did more than just show up and terraform worlds for us. Now, if it actually spoke or if it emailed over a .zip file or whatever we don't know. We really really don't know if it told us about The Darkeness. I kinda think it didn't. If we'd known extinction was coming we'd have built fortresses on other worlds instead of cities and academies.

The book series The Way of Kings by Brandon Sanderson reminds me a little bit of what we know about the Traveller sacrificing itself for Humanity. I wonder if we are in a similar situation to that.

Explain. I'm not sure I'm tracking with you on that connection. :)

3. In the Golden Age we had already built Warminds. We already had solar system patrols ready to engage enemies. I don't see the Golden Age as an age of militarization but its clear it also wasn't a Star Trek utopia. The interesting question is why have these things? The Traveler is said to have shared knowledge with Humanity. Could it have told us of the Darkness?

Do we have any evidence that the Traveller actually spoke with Humanity? Perhaps we learned technologies from the Traveller simply by the fact that the Traveller existed or from creations of the Traveller like the Ghosts? In which case we couldn't have known about the darkness until it was too late.

Just to return to this, I found the evidence by accident tonight. Some guy named Jason Jones said this during an interview:

We don’t know if the Traveler was a ship, or a god, or a moon, or whatever, but we know this thing came and we know that it settled on Mars and that it began to share its amazing technology with us, and a city grew up around it, and all this.

Also, interestingly enough:

" Titans, Hunters, and Warlocks have finally returned to our long-lost worlds, only to find out we are not alone."

So this leads me to believe that many of these other species were not present when the Darkness first attacked Humanity and the Traveler.

So this statement here from Bungie is very interesting.

"In our darkest days, Humans, Exos, and Awoken found the Traveler where it made its last stand, low above Earth, silent and immobile. We built this City – our last – within its protective Shield, fighting countless wars to keep its peace. From that dark age, the Guardians of the City were born."

So, breaking that down:
1) The Traveler makes his last stand right above Earth.
2) Humans, Exos, and Awoken flood under his shield and begin to build The City.
3) Humanity fought "countless wars" to keep the City protected and standing.
(What would make the writers say "Countless wars"?)
4) The Guardians are a product of the defense of the City. Ergo, there were NO Guardians before the City was built.

Close, but:

The first Titans built the Wall, and gave their lives to defend it. Now, you stand in the same high place, steadfast and sure, protecting all who shelter in your shadow. You hail from a long line of heroes, forged from strength and sacrifice. Our enemies may be deadly and merciless, but so are you.

So Guardians predated The City... or at least The City as we now know it. I think the Traveler settled over a city... just the only one it could reach after the battle and that city became The City.

They came from the wild lands, gathering in secret enclaves, slipping through the howling ruins of shattered cities, hoping to find the coast, find a ship, pick up the trail of an impossible dream. From the deep black came the Awoken, their eyes haunted. Exos marched in the refugee columns, cloaked in moss and shattered memories. And among them came the Ghosts, beginning their search. It was a time of vast suffering and terrible evil. But there was one hope: the promise of a refuge beneath the Traveler.

I figure Earth was left in a state of chaos after The Traveler drove away The Darkness. Billions dead, but still not a small number left alive. London, Old Chicago, and other cities not razed might have changed into the battlegrounds of warlords. I'd expect massive shortages of food, water, power. There might have been slavery and all kinds of abuses going on as those with power and with guns tried to gain whatever margin of safety they could. And remember, we know that The Fallen at least were making raids... all the more reason to consolidate whatever power you can.

As the second Grimoire quote says, even The Traveler would have become a hoped for promise. Ten years after the collapse people might still be wondering about what happened to The Traveler. Thirty years out with no one having seen it would become that the older generations knew about but something the younger had no first hand knowledge of. Hundred of years later (our Ghost says he been looking for us for centuries) and The Traveler would be all but a legend for people who didn't live under it.

On the brighter side, we'd have Ghosts all around the world reviving Guardians. Word of The City would get out, even if it was only a promise, a hope, or a legend. People would flock towards a supposed last safe city... if they were allowed to. If they could make the journey. Even in 2014 I would have to strain all my resources to relocate my life to Puerto Princessa where we think The Traveler is located. Imagine trying to do it with no airlines, no friendly cities, no reliable power or water or shelter. And with "terrible evil" lurking about in the forms of your fellow man as well as marauding space pirates or worse!

For a bit more on these things see my Speculation Saturday series. I think you'll find them interesting if you haven't already read them. :)