First impressions suggest a co-op experience close in nature to those that have gone before - but only because of the nature of the opening brace of campaign chapters. These are entirely linear in nature and 343’s strategy in keeping players together is simple: there are certain ‘points of no return’ - such as passing a door that permanently closes behind you, or kicking off a new cutscene, that reset the positioning for all players. With that in mind, I never felt that the game was artificially keeping us closer together, it felt like a classic Halo co-op experience. Obviously, this changes in the open world simply because it has to, with 343 setting up what it calls an Area of Operation - or AOO. This is roughly defined as a maximum distance of 300 metres between players, with warnings starting to kick in at around the 250m metre mark. Once too far apart, the player furthest away from the next objective is auto-killed, spawning closer to his counterpart. The end result is that freedom is curtailed, but the fireteam is kept together, essentially forcing a focus on the next target. Sticking close to one another and clearing objectives together at the same time is immensely satisfying. Teaming up on enemies, working together, or just even criss-crossing the terrain together feels natural and fun much like it would in any previous Halo title before - and perhaps even more so, as crossing the larger swathes of terrain this game has is a bit lonely in single-player, but actually enjoyable in a co-op setting when one person can be in the gunner seat of a warthog and the other in the driver seat, for example. In terms of actual network stability, we put this through its paces by setting up a two-player campaign co-op game with myself in Berlin, with my colleague Oliver Mackenzie playing in British Columbia, Canada - an 8,000km distance between us. We also tested on wildly different PC systems, with myself running a mainstream Ryzen 5 3600/RTX 2060 unit up against Oliver on Steam Deck (with Halo Infinite running under Windows). Despite limiting testing to PCs of various configurations, console owners are invited to the party too, of course, with cross-play across systems fully supported - just as it is in the standard multiplayer modes. In terms of actual gameplay, everything worked just fine, especially in the campaign’s opening linear chapters. Despite the large distance in-between us, de-syncs, latency and other jitters were surprisingly minimal during play. Importantly, there wasn’t the kind of noticeable input latency to non-host players we have seen in titles found in the Master Chief Collection. Despite running at close to 120fps on my unit and the Steam Deck locked to 30fps, in-game latency measured from firing a weapon to seeing its billet impact was also matched on both systems at 166ms. The one area where latency became noticeable visually was when throwing objects in first-person, which has a synced network representation. So, throwing explosion power cores for example, shows a visual lag when leaving the hands, which looks odd. Despite that, it does not get in the way of the gameplay as they still hit where you aimed them - it’s just that the process looks rather odd. There are issues moving into the open world, but fundamentally, that seems to be because of Halo’s bizarrely high PC system requirements. I had to clamp performance down to 60fps for a consistent run of play on my Ryzen 5 3600-based system, while the Steam Deck was plagued with tremendous stutter, even on medium settings with a capped 30fps - something that happens regardless of whether you’re planning online or offline. Obviously, local performance issues have grave implications for the individual player, but as Halo Infinite runs with dedicated servers, this does not seem to impact other people in the same game instance. I did see some variations in latency between us, however, when we switched to more powerful hardware - this seems to be related to how close the user is to the dedicated server, with Oliver having a lower latency experience in North America, than I was in Europe. So, is the campaign co-op option looking good? Yes. Is it ready to roll-out for all users? I’d say not, as there are a number of bugs in the experience as it stands. While latency is reasonable, we experienced two game lock-ups in four hours of play, always happening around loading. In all instances we had to manually force quit the game from Windows and restart our co-op session. Ultimately though, I had a blast going back to the game. Despite the limitations of co-op play within an open world, the experience is excellent overall - and it’s definitely the way I want to complete my campaign playthrough of Halo Infinite. I’ve previously completed every Halo campaign in co-op, which made its omission at launch with Halo Infinite so disappointing - but even if you have already completed it, the addition of campaign co-op is definitely a game-changer and I look forward to the upgrade’s official release.