Resident Evil is a series that's always dealt with the shady Umbrella Corporation creating reprehensible abominations inside secret laboratories, so we imagine that Capcom will be wanting to avoid conducting a similar experiment with Operation Raccoon City, Slant Six Games' 'what if?' spin-off that proudly plays fast and loose with the Resident Evil mythos. On paper, it's a freakish mutant anomaly, taking the traditional third-person shooter template and draping it in Resident Evil clothing. But of course, there's a little more to it than that glib summation would have you believe.

While it's perturbing for some that a franchise with Resident Evil's slow-burn survival horror heritage has become such an action-oriented beast in recent years - and Resident Evil: Operation Raccoon City is inarguably the purest iteration of the series' rebirth as action-packed shooter - having played the majority of the first half of the campaign, it transpires that Operation Raccoon City is actually a pretty robust shooter, with some slight jump scares here and there. Playable as a solo experience or in 4-player co-op with a moderately compelling story and satisfying XP system that grants you points to spend on new abilities and weapons, the key ingredients are in place to make RE: ORC a worthwhile shooter.

And in a world where we all know that Resident Evil 6 is now most definitely on the cards and coming in November this year no less, Operation Raccoon City needs to stand out as a game that deserves to be on Resident Evil fans' radars. Although it's not strictly canon, it's still an intriguing prospect helped in no small part by the inclusion of familiar locations and a boatload of zombies. In the opening missions, you'll encounter the likes of a G-Virus infected William Birkin, as you witness the outbreak with Hunk and his team in the Umbrella laboratories. You'll then head out onto the streets of Raccoon City, through the hospital where you'll first run into faceless troops from the rival Spec Ops team that's been sent in to prevent your team of Umbrella Security Service operatives from covering up the incident, and everything moves along at a nice, brisk pace.

Much of what we've played of Operation Raccoon City's campaign involves collecting data, destroying evidence, shooting countless zombies and Spec Ops troopers, and completing somewhat hackneyed objectives like collecting keycards. Yes, keycards. In single-player, this gets a little tiresome, but the strength of the shooter mechanics and the appeal of the characters manages to keep things exciting. But only just.

Before each mission, you get to choose your loadout from a vast array of primary weapons - covering all the bases from pump-action shotguns, to submachine guns and bolt-action rifles – and a few secondary handguns accessed with a tap of L1. Each character also has their own specialisations and abilities that you can purchase to augment your loadout, so a character like Spectre for instance, who specialises in surveillance, can acquire abilities that enable him to keep track of enemies on the mini-map or in the field by utilising thermal vision. The team's scientist, Four Eyes meanwhile can possess zombies and control them. With six characters to choose from, each with five specific abilities apiece, there's more than enough to experiment with.

Our hands-on with Resident Evil: ORC's first four campaign missions takes us through some impenetrably dark environments, so the first order of business is to crank up the gamma settings just so we can see where the hell we're going. The good news is that it all looks the way it should, with cold and clinical lab spaces, rusting warehouses, messy governmental buildings with mahogany doors and desolate streets. It's all unmistakeably Resi, despite being a departure in gameplay terms, and the presence of fan favourite monsters will appease all but the most die-hard Resident Evil pedants. The first four missions alone see tussles with Birkin, the nigh-on invincible Tyrant fella (Mr. X) in his immaculate trenchcoat and a minigun-toting Nemesis from Resident Evil 3, who you're tasked with wrangling and injecting with a parasite for Umbrella, so that they can regain control of him. No mean feat. We wonder what an Umbrella pension is like? It had better be bloody good on the basis of some of the suicidal objectives you're commanded to fulfil.

And so having dispatched an army of lickers in a flaming room, killed hundreds of zombies and given some of the Spec Ops crew an early retirement, it's here that our hands-on must end. We could tell you more, but then we'd have to kill you, and besides, it'd spoil the later campaign missions. Like our last hands-on, Operation Raccoon City is still looking the part and it's still definitely more fun in co-op, despite some pretty sturdy buddy AI. Again, the enemy AI still isn't quite up to scratch, although it seems to have improved since last time, and there are some genuinely great moments like having to traverse a street strewn with burning cars and other detritus while laser-sighted snipers flank the streets. The boss moments however, stick out like a sore thumb at present and could do with being a bit less about patience-testing attrition and more about strategy.

There's still time for Slant Six to tighten up these areas though, and on the whole, Resident Evil: ORC is bearing up rather well. As a co-operative experience, it ought to deliver the goods, and as a shooter it's remarkably solid, which is heartening this close to release. However, there is still an all-pervading sense that Operation Raccoon City is in essence a fairly well-crafted shooter that just happens to have Resident Evil as its theme, but if the rest of the story proves to compel, and multiplayer does the job, it could be worth investing in when it starts spreading its fetid infection this March.