Polygon has a fantastic article on Crackdown 3 and cloud computing.
too long. go read it!
Crackdown 3 (finally) proves why Microsoft put Xbox One's head in the cloud
This is the havoc of Crackdown 3's online multiplayer mode. In a persistent, destructible city, I can reduce everything to rubble. Or I can chop down a building or two, head to the other side of the city and return to continue the demolition with my friends.
It is built around pure, unadulterated destruction. And it is only possible because of a technology that Microsoft once touted more or less every time it mentioned its latest and greatest console, the Xbox One: cloud-based computing.
The tech was supposed to be a huge differentiator over the Xbox One's competitors, but at best we've seen glances and hints since the console's reveal more than two years ago. Last week, Microsoft made the cloud rain with Crackdown 3, and they wanted me to know it. Its developers created ways to show how it worked, what it was doing, how it made made the impossible possible. It was deeply impressive. And I wouldn't have had a clue that any of this was happening unless they'd pointed it out.
SELLING THE CLOUD
The cloud's quiet, nebulous nature is part of the reason that, over the last year or so, Microsoft's much-touted cloud services, once lauded as a feature that could "effectively over time" make the Xbox One "more powerful" faded into the background. There wasn't much to see. Even when games were built using the technology, they often didn't seem all that different than what came before them. Microsoft's cloud became a thing you could hear about, again, and shrug off.
Respawn Entertainment's Titanfall, for example, is built upon Microsoft's cloud services. But to players, the technology is transparent. You just play Titanfall, and although engineer Jon Shiring has long said that offloading things to the cloud allows for "a bigger world, more physics, lots of AI, and potentially a lot more than that," Titanfall behaves more or less like you'd expect a multiplayer game to behave. The technology behind the scenes works so well that you don't have to think about it. Out of sight, out of mind.
"You say 'cloud,' you can talk about it in a nebulous way, and it doesn't really have an instantiation that a gamer is going to say, 'Oh I get the value of that,'" Spencer told Polygon at Gamescom. "And, frankly, I stopped talking about it, not because we weren't still working on things like Crackdown, but I knew that until I had something where I could put it in front of people and say, 'This is what we mean,' and then let people decide based on the quality of what they saw, 'Hey, this is actually working for me or it's not.' So I went, 'I'm going to be cloud-free for a while until we actually have something to demo.'"
PLANNING TO BLOW UP A CITY
Crackdown 3 predates the Xbox One. Before Microsoft had new hardware, the game grew out of a desire not only to continue the franchise, but to do so with new technologies.
"Crackdown started actually before we launched Xbox One, but we had the idea around cloud and how we wanted to use it in the game and I thought it was a natural fit to the creative fabric of the game. It's really come together.
"We have to be very clear about this," franchise creator Dave Jones said after demoing the game at Gamescom. "In the multiplayer, it's 100 percent destructible, and it's forever — forever, as long as the game lasts. We haven't said what structure of the multiplayer game is yet, but it is … 100 percent destructible environments and 100 percent persistent over whatever sort of game session we're talking about."
To be clear, there is destructibility in the campaign, but it's toned down for practical reasons. If you wandered around and laid waste to the town, you'd destroy missions alongside buildings. Plus, you know, you're trying to save the city in the story, not destroy it.
But how? The developers demonstrated what was happening behind the scenes with a simple developer mode they toggled on. As Jones and a few others ran around in the game world, the skyscrapers had color overlays. One on the right had a green hue, another magenta. Each color, Jones explained, represents a different server in charge of the building. A little Xbox One logo hovered in the top left corner of the screen. Another special user interface element sat next to the logo: a single horizontal bar about an inch long.
Everyone began shooting up the world. As the explosions expanded and debris began to fall, the bar began filling up like a progress bar on a computer. This, Jones explained, represents the total processing power of the machine he was playing on. It was running out of space quickly.
Then it ran out of space entirely.
" "We always have the compute power on demand" "
At that moment, another horizontal bar bar appeared below it, but without the Xbox One logo. This, he explained, represents a server living in the cloud that automatically kicked in when the local machine reached its limits.
They kept shooting, kept causing more destruction, kept chipping away at the dual skyscrapers. The deeper the destruction, the bigger the explosions, the more power Crackdown 3 required. When the server's horizontal bar maxed out, it added another, represented by a progress bar beneath it. And another. And another. The game didn't so much as hitch as the buildings fell and more and more servers made it happen.
This is the cloud, and Crackdown 3 is all up in it.
Cool. But why?
This is all all necessary, they tell me, because there's just no way to reliably track chaos on this scale by doing things the old way.
For years, making multiplayer work was fairly straightforward, at least conceptually. Say you’re playing a round of team deathmatch with eight other players, each on their own consoles spread out across the world. One of those eight consoles becomes the host, basically the King Console that all information passes through. Every other console is a client that relies on King Console to provide it information like where players stand in the world, where the bullets are flying, that kind of stuff.
That host/client relationship is necessary because things get messy. The consoles will disagree about where your character is standing at some point. King Console has the final say, determines the canonical location.
It’s not a trivial problem to solve, but it’s been a rock solid system for years. In a multiplayer match in, say, Halo 3, there’s a relatively small amount of information to keep in sync. The tried and true system works pretty well. But in a game like Crackdown 3, where the game models and monitors every little sliver of debris flying around an entire city, it’s exponentially more difficult to sync across multiple consoles. Game makers can surpass some of the limitations and add more theoretical reliability by enlisting dedicated servers to host matches, but those won’t solve every problem.
And, at a certain point, they also run up against the limits of console hardware. Modeling physics is hardware intensive. Keeping track of four goofballs with rocket launchers firing every few seconds, accurately modeling the destruction each blast causes and syncing with such speed that nobody playing can tell there’s any lag is far more than even a tricked out PC can handle.
Microsoft’s solution: Offload calculations and physics modeling to the cloud, where servers do the math that your Xbox One can’t — all while keeping everyone in sync.
TECHNOLOGY ISN'T FUN
I spent maybe 15 minutes running around Crackdown 3's streets, blowing stuff up, using developer tools to fly above buildings, watching the destruction flow. At one point, while standing on top of a building probably 20 stories tall, I looked far into the distance and a skyscraper with a curved, cone-like top caught my eye. I aimed and fired, just to see if my shot would land. It did. I watched a tiny explosion plume miles away. I chuckled.
It is clearly nowhere close to being done, and I only saw a tiny part of it. What I played was an alpha at best, an impressive, functioning proof of concept running in a highly controlled environment. It's no guarantee that it will perform this well when Crackdown 3 arrives worldwide next year.
But I didn't consider it terribly impressive until its developers let me look underneath the hood.
"Crackdown is a perfect example of a game that we decided to start on with a real technical challenge around Dave's passion for cloud and our Crackdown passion, say 'Is there a way to bring these two together?'" Spencer said. "The chances that that would have worked probably less than 50/50. Even though we knew we had Crackdown and there was a fanbase there, and it's nice to be able to get here and actually see it show up and now we're talking about the date of the game and you can see code really running and people playing it."
But, again, as impressive as the technology is, it's conceivable that a large number of future Crackdown 3 players will never know, care about or understand why they can level every building in a city with three of thier buddies, just for fun. It's good to know that the people behind the game, proud though they are of the back end, seem to understand that, too.