I was recently able to sit down for a game of Mass Effect 3’s four-player co-op mode, Galaxy At War. So, what is it, exactly? What does it add to the game? And is it going to distract you from the single player? I think I’ve answered that all below, along with four brand new screenshots you can click on to enlarge.

My position before having a go was one of disinterest. The Mass Effect series is, for me, a single-player game, because – well – that’s what it’s been so far. As a massive fan of single-player, narrative-driven gaming, it seemed to me the very last thing ME3 needed was an online distraction. Especially one that directly affects the single-player game. Then I played it.

Galaxy At War isn’t anything groundbreaking. Then, it’s really not trying to be. It’s not intended to be a reason why someone might buy the game. This isn’t Battlefield 3’s multiplayer compared to its single-player. I’m relieved to say Mass Effect 3 is clearly still intended to be primarily a single-player experience, optionally augmented by the co-op. And it’s pretty fun. (I should add at this point that I was playing this on a 360, as no PC code was available.)

Think, Left 4 Dead, but you don’t go anywhere, and you can’t pick up weapons, and, er, it’s got four players. The level we played was set on a fairly generic, grey-and-white multi-level platforms, interior and exterior. It was certainly unremarkable. But quickly the four of us – three games hacks and a BioWare employee – were being attacked by waves of Reapers and Geth.

Waves is the key here. It’s about surviving as many waves as you can, before your inevitable death. The more of them you survive, and the more you get done, the more points you get to carry over to your SP story. Which lends it the arcade-feel that ensures it knows its place.

Those things to get done – they’re not that complicated, really. The examples we had were to “hack” a computer, and “hold” an area. Which was really to have the four of us try to stay in a glowing circle within a time limit. It forces a more exciting time of fighting, putting us in the open and requiring more imaginative combat to get through, with bonuses for completion.

And it’s the possibility for that more imaginative combat that makes the co-op more worthwhile. As you’ll remember from Mass Effect 2, fighting with your gang became a lot more fun for being able to fling someone in the air, then empty a barrage of blasts into their spinning body. Here you get to do that as a team, and effective use of skills and weapons becomes very rewarding. I might grab someone with biotics and helpfully float them up so someone with a bloody great shotgun can blow their belly out. This becomes even more crucial when you’re fighting some of the game’s larger enemies, who can prove a real obstacle to completing a wave.

At one point, on a balcony above our squad, amongst the very many regular Reaper enemies appeared a Brute – a giant beast of a creature, covered in shields. And he was being defended by a couple of Banshees – flying creatures with crazy-strong barriers cast around them. It was certainly the most epic stage of our twenty minute game. And it forced decent teamwork to get through – there was no way to deal any damage to any of them without our carefully taking out the Brute’s shields, then others piling in to do damage until they were repaired. Meanwhile the Banshees would occasionally have to drop their barriers, allowing a chance to pick away at their health too. Alone, none of us would have scratched them. So their eventual defeat was pretty damned satisfying.

Less satisfying is the complete lack of a sense of progress. Because the level was really a small arena, completing a wave didn’t offer you the reward of moving on, feeling like you’d gotten somewhere. Instead you started a new, more difficult fight pretty much where you already were. And with spare ammo pretty much only in one place, the outer edges of the level became pretty much out of bounds. (I really hope there’s some tweaking of ammo distribution before it’s released. Armed only with a pretty useless spare pop gun, and a shotgun, I could only carry ten bullets at a time, which made for some fairly boring trips back and forth to the ammo bin.)

So yes, everyone gets two weapons. A back-up, and your main. And along with those you have three special abilities. It’s a stripped down version of the regular ME interface, simplified such that it doesn’t require any fiddling at all, which makes sense in a context where you can’t pause the action. Also making life easier, there’s no friendly fire, which is a good job in the frantic mess of bullets, blasts and biotics.

Death means you’re out for the rest of the wave, but then rejoin your gang once a new lot of enemies appear from every direction. But should everyone fall, you’re done. We reached something like Wave 13 before eventually the four of us gave up the ghost, my valiant lone effort at the last proving a little futile against quite so many Reapers and no ammo. We were told by the BioWare chap that we’d gotten far further than anyone else that day, which I assumed he says to all the girls and boys until I saw another group uselessly flailing about and dying after four or five. Which is to say, me and the two strangers I sat next to, are best at Galaxy At War.

While you’re individually scored as you play, that’s purely for bragging rights. The score you carry over to your single-player game will be your team’s combined efforts, meaning even if you’re a cack-handed buffoon, you’ll still not have wasted your time. It seems a smart move, but I’m sure will lead to some disgruntled players.

It’s ultimately a pretty meaningless thing. But where the fun comes from is in realising it’s meant to be. It’s popcorn, alongside the square meal of the single-player game (assuming it’s of the same standard as the previous two – we’ve not played anything of the SP game yet.) It’s not going to be the sort of thing people will be playing long after the game’s been released. But it’s certainly an enjoyable time, with its escalating difficulty and arcade sensibilities. Plus, gosh, the game is looking gorgeous.