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• October

  06

  Blog > Building Co-op From The Ground Up

Welcome back everyone! As promised, our latest blog is dedicated to Co-Op, which is arguably one of the largest undertakings this team has ever tackled in a game. I sat down with our Producer, Dan Bunting, who sheds light on the size and scope of engineering co-op, along with the risks and benefits associated with introducing the feature into the Call of Duty franchise for the first time. First, a little background on co-op and what it means to Call of Duty gameplay...

Finding a Co-Op game will work as you'd expect. On the 360 and PS3, you'll be able to create private Co-Op games, or find public Co-Op games with anyone else around the world. For PC players, we created Co-Op game lobbies, so when you join a Co-Op server in-game – instead of immediately connecting to a server – you join that server's lobby. The host will then choose the settings, and start the game.

Now, what exactly will Call of Duty: World at War bring the players in the way of Co-Op? Let's see... Unfortunately I can't talk about everything just yet; however, I can tell you that we do have a third Co-Op experience in store, which I promise is like nothing you've ever seen before in a Call of Duty game, but for now...

Campaign Co-Op
Play Co-Op through campaign levels you can experience in Single Player, but with up to three others (four-player online, or two-player local split-screen). As soon as we got Campaign mode up-and-running, we starting building it out further and one way to do that was with Competitive Co-Op...

Competitive Co-Op
It's Campaign Co-Op, but with a very important twist: you play cooperatively through single-player campaign levels, while competing with your partners for points. Each kill will award you with points; headshots and other more difficult feats are worth more than a basic kill, you go on streaks to create point multipliers, and squad mechanics also award points (such as reviving a downed teammate). There is a score board now, and at the end of the match there are Match Bonuses as you'd expect. What's more, is that you are earning XP (experience points) – any XP earned in Co-Op will add to your global rank, which translates to XP and unlocks in Competitive Multiplayer. So before playing Competitive Multiplayer, if you gained 10 levels in Co-Op, you would have all your level 10 unlocks when you logged into Multiplayer (level 10 weapons, perks, attachments, etc).

Dan Bunting: Engaging the Opportunity
When we began the project, we immediately identified co-op as a huge opportunity to deliver something the community has wanted for years. The challenge was incredibly exciting and intimidating at the same time. After all, there is a certain trend-setting standard that you have to live up to with each new Call of Duty title – this would be the first time in the title’s history that players would be able to play online together through the kinds of levels that were previously only playable in Single Player. Because of this opportunity and the challenge that came with it, we were motivated to pour all of our energy into it and make it the best co-op experience possible. We dug deep into the challenge and ate it up from Day One.

Engineering
On the engineering side during the planning stages of the project, we contemplated various methods of implementing co-op, including merging the single-player and multiplayer executables, making co-op a part of the multiplayer game, or building networking into the single-player game. The first option of merging the executables would have been far too risky for this project; however, one that we plan to keep on the table for possible future use.

The second option of making co-op a part of the multiplayer game and essentially just delivering co-op game modes was interesting from a design perspective, but ultimately we felt that would not have lived up to the Call of Duty community’s expectations. People want to play the campaign with their friends – “No one fights alone” has been the COD tagline since the game was first released in 2003.

We chose the third option, which meant building online functionality in every facet of the game. This still gave us the flexibility to create co-op game modes, but didn’t eliminate our ability to build online co-op gameplay into the story campaign. Our lead online engineer, Alex Conserva, spent about three months on the initial work. This got us to a place where we could play the game cooperatively, but there were plenty of bugs to shake out with this complete system overhaul.

Once we conquered the early technical hurdles, we had a fully-playable co-op game within the first year of development, which was an incredible feat – my hat goes off to our engineering team for achieving the seemingly insurmountable. I’ve got big time respect for them.

Design
With the co-op game in place, we were able to begin design iteration. Some of the early prototypes included wide open “free-roaming” level designs where co-op players could fight through a variety of engagements in different areas of the level, but they would all move towards the same end objective.

For a first pass, these prototype levels taught us a lot of early lessons about what the co-op experience should be, and the free-roaming open world wasn’t the right direction. We found that players in this setting would end up playing by themselves through the levels with only a minor awareness that they were actually playing the game with another player. This didn’t feel like a Call of Duty co-op experience, so we quickly moved away from this design.

The next iterations had players fighting within close proximity to one another but offering many different choices and angles of attack on the same combat event and a variety of weapons by which they could accomplish their goal. This felt good – it was very much a Call of Duty experience and the right way to go.

The final touches came with iteration on the variety of ways in which you can play co-op. Call of Duty gameplay is rooted in arcade games – the arcade style of play is just embedded within a lot of intense cinematic moments and story. Additionally, competitive multiplayer is a staple of the franchise, so we thought it would be cool to bring a bit of the MP vibe into co-op.

As such, we wanted to provide players with an alternative to the straightforward cooperative campaign experience – thus, competitive co-op was born. When players start competing with one another for anything, the gameplay becomes exponentially more addictive. And this addictive nature of gameplay is what resulted in this new mode – I knew it was a hit when everyone in the office started playing it in their down time.

Dan wrapped up our meeting with some additional co-op features that we haven't been talking about publicly just yet, but included features like gameplay modifiers, Co-Op specific challenges, an additional co-op game mode, and more. Treyarch is really excited about the breadth of our Co-Op experience. Come this November, I think you'll get an idea for what I'm talking about.

Remember, October offers up two BETA's (an Xbox 360 BETA and a PC BETA), so if you want to secure your BETA key, be sure to pre-order the game at GameStop if you're in the U.S. For everyone else, sign up at CallOfDuty.com to save your place in line!

Hope to see you on the battlefield,

-JD