We all remember the first time we played a Halo campaign co-operatively.

Once upon a time, two cryo tubes opened aboard the UNSC Pillar of Autumn and you escaped onto the surface of Alpha Halo together, accidentally meleeing your partner in the back as the level began (just me, huh).

Giving the Covenant back their bomb was a team effort; your road to Recon was a path forged together through the unfinished structures of Installation 08 and the cityscape of New Mombasa. You did not fall on Reach—nor to the esoteric shores of Requiem—alone, and the Mjolnir-armored boots of the legendary Blue Team and Fireteam Osiris were filled with those of your friends.

And now, at last, whether you’ve been on this great journey from the start or are just joining us now, it’s time to fire up your friends list and send out that party invitation. Zeta Halo awaits your arrival...

FOUR TIMES THE FUN

Campaign Network Co-Op for Halo Infinite is on its way and you’ll soon be able to take the fight to the Banished with your friends and family in the upcoming flight, which is targeted to run from the week of July 11.

We’re joined today by Isaac Bender (Principal Software Engineering Lead) and John Mulkey (Lead World Designer) to discuss all the details you need to know about Network Co-Op for Halo Infinite.

First of all, a warm welcome to you both! Y’know, they say that Halo is always better when you play with friends—it's certainly a mantra that Joseph Staten has echoed as the team has worked hard to bring this beloved feature to the game. What are some of your fondest campaign co-op memories?

Mulkey: Well, I would have to say it's Halo: Combat Evolved that I remember most fondly. I was working at Monolith Studios at the time, and they had gifted me an Xbox and a copy of Halo right at launch. It was the Friday night of a weekend that some friends from Portland were coming up to stay for a visit. When I got home, they were already there. I was cordial and all but made it clear that we really needed to set this thing up and at least try it out.

So... I got everything set up, Dave and I sat down and launched into Halo co-op and did not stop until it was deep into the wee hours of the morning. Significant others were not impressed.

The next morning was ridiculous. Both Dave and I were drinking coffee, chatting with the families, but both gauging how soon it was acceptable to return to the game. We continued playing all day and into the morning again. Now it is Sunday morning, and they are going to be heading back home. Dave and I started playing again that morning, we were so close to finishing the campaign—we were on the final level while his wife was loading the car, none too pleased at our behavior.

Dave had to leave before we finished, but man, what an introduction to Halo. I will never forget how it grabbed me and has not let go ever since.

Isaac: One of my most memorable co-op experiences is probably Halo 3 on Heroic. The Warthog run at the end of the mission simply titled “Halo” is a great time when you’re playing with friends, finishing the fight together brought with it a very special kind of chaos.

It actually has quite a bit in common with “The Road” in Halo Infinite. I’ve always loved the vehicle-based missions in Halo and I’m glad that we’ll be able to fully realize the potential of vehicles in Campaign once Co-Op is out for everyone to play!

As we’ve been testing Campaign Network Co-Op in Halo Infinite, what are some of the crazy things that have happened during your time playing?

Mulkey: We've been having a ton of fun together, pulling off heroic feats only possible when playing with your friends.

A natural part of development is some of the crazy bugs that present themselves, so this particular memory was a fun one for us. Very early in testing, we were replaying Ransom Keep in Co-Op with some late-game gear. One of us was in a Wasp providing air support while the other went to raise the fuel silos so they could be destroyed by the Wasp.

When I activated the plunger switch to raise the silos, everything played out fine for me, but my buddy in the Wasp was teleported to the ground and left with one wing buried in the dirt spinning relentlessly in circles. After verifying that this was indeed a bug and not just his poor piloting skills, we umm... fixed that!

Campaign co-op is such a beloved feature of the Halo experience, we knew it was definitely something Halo Infinite would and should have—but the road to making it a reality would extend a bit beyond launch. What were some of the challenges the team faced here?

Mulkey: One of the greatest creative challenges has been in how we support this new, more open experience and the many new questions that raised. How do we set up a shared world state? How do we keep the Fireteam together? How do we determine intent and mission focus? How do we prevent sequence breaking the narrative?

Isaac: One of our core principles is that we don’t want to require you to have an isolated Co-Op save. Of course, you can use a separate save slot for Co-Op if you want to, but we wanted to give players the option to have Co-Op progress count toward your “main” playthrough, if that’s how you want to play.

We also wanted everyone’s progress to count toward their own saves, regardless of who the Fireteam leader is. I’ve played a number of co-op games where “Player 2’s” progress essentially doesn’t count, and I’ve always found that disappointing.

That raises a really interesting point. How does Infinite’s Network Co-Op handle different game states for the players in the game? Is everyone progressing the Fireteam leader’s world? Each their own? Does each player’s progression carry forward to their own personal session beyond Co-Op?

Mulkey: This is one of the areas I am really excited about. The goal going in was to “allow everyone to play their campaigns together.” This meant that all progress made in the game, regardless of it being through Solo or Co-Op play, would be retained.

I could be playing Solo campaign, jump into a Co-Op session for a few hours, then launch back into Solo play and all the mission progress, acquired collectibles, equipment found, achievements earned, and upgrades made in either session would be intact. Gone are the days of playing someone else's game while earning no progress.

The way we are handling this is through something we internally refer to as “No Spartan Left Behind”. When players join the Fireteam and choose their save slots to play on, the game aggregates the states of all missions across those saves and sets up a world state in which any missions completed by all Fireteam members are marked as complete while any missions not completed by all are marked as incomplete.

Isaac: You can think of this system as creating a version of the world that’s like the “lowest common denominator” (or “intersection,” if you’re into set theory) of everyone’s Campaign progress. This way, no matter what you do, no one is completing missions out of order.

What this means is that any unlocks you find in Co-Op are retained in single-player. So, if you’re having a really hard time collecting a Skull, you can get in a game with a friend, and if they collect it while you’re in that session, you’ll get it too!

Network Co-Op is coming to the Xbox One, Xbox Series X|S, and PC—are there any differences in the overall experience that players should expect depending on which platform they’re on?

Mulkey: The gameplay experience you will have will be the same regardless of platform. This is an imperative requirement in supporting Co-Op crossplay.

Isaac: Crossplay is fully supported. There are differences in graphics quality and framerate, but this applies equally to single-player.

What are the different configurations of players/platforms that are supported with Infinite’s network co-op?

Isaac: Any combination of PCs and Xboxes up to 4 players are supported, as is playing over Xbox Cloud Gaming. All Co-Op games are hosted on dedicated servers.

How do I party up with my friends to jump into some Campaign Network Co-Op?

Isaac: You’ll use the same system players are already familiar with from Halo Infinite’s Multiplayer to form a Fireteam. Once your Fireteam is formed, you can just pick “Start Co-Op” from the main menu. It’s that easy!

As I mentioned above, everyone’s progress counts! So you’ll pick which save slot you want your Co-Op progress to count towards. After everyone has picked their save slot, you’ll get a summary of where your team will be starting, based on the “No Spartan Left Behind” system that I described above.

There have been lots of different flavors to Campaign Co-Op in Halo in the past. In some entries, you’re a squad of Master Chiefs (or Arbiters), whereas in others, additional characters are present. What approach does Halo Infinite take to campaign co-op here and why?

Mulkey: In Halo Infinite, everyone is Chief while playing Campaign Co-Op.

This is in support of the goal that Co-Op allows players to play their campaigns together. All progress made is progress kept in the Campaign regardless of it being Solo or Co-Op play, so in both (much like in Halo: CE, Halo 2, and Halo 4), Chief is Chief making his way through Zeta Halo.

The world in Halo Infinite is incredibly expansive. Can I decide to go liberate a FOB while my Co-Op buddy heads in the other direction to take down a high-value target? How exactly does the game handle it if players get too far apart in the open world? How will it handle players being separated in the more enclosed missions?

Mulkey: The whole point of playing together is just that—playing together! Co-Op allows a group of friends to join up as a Fireteam and tackle the various locations on the ring together.

To that end, we have established what is called “Area-Of-Operations” (AOO). This is the maximum distance that players in a Fireteam can stray from one another as they explore and tackle the challenges of Zeta Halo. If you stray too far from your Fireteam, you will get a warning to return to the team. If you ignore that warning and continue, you will be killed for going AWOL and be spawned back on your nearest teammate.

How large are the Area-Of-Operations?

Isaac: It’s an interesting balance to strike because we want players to have the fun of fighting together, but we also don’t want it to feel like the game is forcing you to be joined at the hip, so to speak.

We landed on tuning the AOO with two values: an inner "warning radius" (800 feet) and an outer "kill radius" (1000 feet).

To give you an idea of that scale in-game: if two of you want to hit a really big objective like the Banished dig site, the AOO will definitely allow you to tackle an objective of that size from opposite sides with room to spare.

How will Spartan Cores (used to upgrade your equipment) affect Campaign Co-Op? Is it the case that if Player 1 upgrades an ability, that is then shared with Player 2?

Isaac: Upgrades and Cores are tracked separately per player. If anyone collects a Core in co-op, then everyone in the Fireteam who had not already collected that Core will get credit for it.

You can then spend your Cores independently, and your Core count and upgrade choices are retained in your chosen save slot.

This means that you get the benefits of working together, but you also have the room for self-expression with your personal playstyle. If one of you wants to focus on upgrading your Drop Wall to protect yourself while your partner gets the Grappleshot melee upgrade to charge into the enemies’ ranks, you can do that.

Speaking of that really cool upgrade to the Grappleshot where you can hold the melee button mid-grapple to do an electrified slam... Can my buddy and I use this on each other in the middle of a group of enemies, like the ultimate Master Chief fist bump?

Mulkey: Oh, absolutely. Do it!

ONCE MORE, WITH FEELING

Halo campaigns aren’t something players tend to go through once, but replay many times over—whether you’re in it for the story, the gameplay, speedrunning, finding tricks and glitches, Skull hunting, and all the other accoutrements that give Halo campaigns a special place in the hearts of many.

It has been a long-time tradition in the Halo franchise that once you complete a mission, you can go back and replay it for fun, to unlock achievements, to find collectibles, and so on. In previous titles, this was a straightforward proposition since those games were assembled from a series of self-contained "levels."

With Halo Infinite, we introduced a more open and explorative element to the campaign paradigm. This necessitated some changes to the way Mission Replay works to ensure we can enable the option to the player while ensuring we maintain the integrity of the experience and the game state.

“Mission Replay” is a feature that’s also coming alongside the Network Co-Op update. Can you explain how that will work?

Mulkey: Mission Replay has always been a mainstay of Halo, and we want to continue that tradition with Halo Infinite. However, the more open nature of Infinite poses new creative challenges that did not exist when missions were broken up into their own discreet levels. You could simply reload that level and replay it.

In Infinite, missions are locations in a much larger playspace of other mission locations. We are leaning on the Tac-Map as your gateway to interacting with individual missions.

In both Solo and Co-Op play, you can open your Tac-Map, highlight a completed mission, and then choose Replay. You will then be prompted to select the difficulty and be offered to activate any Skulls you (or your teammates) have collected.

Setting a mission to replay resets it and teleports you (and your fireteam) to the location to tackle the challenge. You are free to wander off to do something else, Fast Travel away, or resume your furthest main mission.

So, let’s say I want to replay Warship Gbraakon—the first mission of the game—after my Co-Op partner and I have collected a bunch of Spartan Cores, will those upgrades carry over to that earlier point in the game?

Mulkey: Yes! This opens up all new ways for players to experience those earlier missions and we can’t wait to see what experiences folks have with that!

One very cool and unexpected side-effect of this upcoming Campaign update is the addition of several brand-new achievements. Where did the inspiration come from? Can you give us an idea of what players can expect?

Mulkey: The new achievements are targeted at the opportunities afforded by both Mission Replay and Co-Op.

Some of the Mission Replay achievements are targeted at immaculate play challenges, while the Co-Op ones revel in the possibilities presented by playing together.

To give you an example of one of them: we challenge you to kill enemies with a Gravity Hammer from the back of a vehicle being driven by your buddy.

Batter up, Spartans—sounds like it’s going to be a blast! Thank you both very much for giving your time to answer our questions about this today, it’s going to be super exciting to see what chaos ensues when everyone gets their hands on this.

Before we let you go, did you have anything you’d like to say to our players?

Mulkey: San Dimas High School Football Rules!!! (I really hope someone out there gets that reference.)

Isaac: Thank you all for playing! We’re excited for you to get hands-on with this experience and we hope you have a great time with it.

And on that note, let’s talk about flighting...

XBOX & STEAM PC NETWORK CO-OP FLIGHTING

We will be flighting this Campaign Network Co-Op and Mission Replay experience through the Halo Insider program from the week of July 11.

We’re looking for Spartans out there to help us put things through their paces in order to ensure that there are no big issues that make it through to the full release.

What are the team’s overall goals for the campaign Network Co-Op flight?

From a technical perspective, our main goal with this flight is to catch any networking issues that are specific to Campaign Co-Op.

What are the requirements and necessary steps for someone to participate in this upcoming flight?

It’s simple! Here's a quick blurb, but keep an eye out for full instructions once the flight is officially underway.

Step 1: Make sure you’re signed up to the Halo Insider program.

Step 2: Ensure you have the entitlement to Halo Infinite (Campaign). (i.e. you have purchased it or have an active Xbox Game Pass subscription)

Step 3: If you’re participating on Xbox, have the Xbox Insider app downloaded, and opt into the Network Co-Op flight program once the flight is live. If you’re playing on Steam, you’ll be sent a unique key via Halo Insider communications to download the flighting build.

Step 4: Launch the build, party up with friends, and jump into Zeta Halo!

Will our progress from the retail game carry-over to the flight build? And vice versa—will anything we unlock or progress during the flight also apply to the retail version of the game?

No, progress will not carry over. The Network Co-Op flight is conducted on a separate build intended to test the features without affecting your existing retail copy of Halo Infinite.

What’s the best way to share feedback or report any issues encountered during the Co-Op flight?

We will, of course, be monitoring feedback that pops up online and on our forums, but any issues you run into should be reported on the Halo Support site.

With all that said, you’re now armed and ready to grab a friend (or three) and take on the Banished when the flight arrives!

As a reminder: we are targeting the week of July 11 for this flight and will keep the community appraised of any updates on that in the coming days. In the meantime, make sure you and your friends are signed up to the Halo Insider program and have everything in place to explore the mysteries of Zeta Halo.

We can't wait to hear your stories!