It's nearing 10pm when I round the corner of a warehouse on Leeds' old industrial quayside to find a trio of young men tearing across a dimly lit car park. They slow up, eyeballing me and my companions at a distance, before one approaches purposefully. Any other night, I'd be mentally flash-forwarding to the Crimewatch reconstruction, but this evening the shadowy urban landscape is framed by a different set of references. "Hey," he greets us in a conspiratorial stage whisper. "Seen any zombies round here?"
In fact, I've seen plenty of them as I've sprinted and sidled my way across the city tonight: a couple shambled behind us through the trees on the university campus; others stalked us in a deserted shopping centre; and had I been a split-second slower racing between the darkened stalls of the town's market, I would surely have felt the hand of an especially agile member of the undead on my shoulder. And you know what that k would have meant... Well, actually, on this occasion, nothing scarier than a cross daubed apologetically on my hand in UV marker pen.
For though the setting is real, the zombie apocalypse unfolding within it is pure fantasy, brought to life by some elaborate stage-management, skilful live performances and a healthy investment of imagination and energy from the 400 or so people who've paid for a shot at "surviving" tonight. The event, called 2.8 Hours Later, is essentially a game of tag for grown-ups. But while the objective – make it from start to finish without getting caught – is within the grasp of your average eight-year-old, everything else about the game has been scaled up in proportion to the expectations and abilities of an over-18s crowd.
Armed with a map, small groups of us are let loose on the streets, where a network of stooges playing survivors drip-feed us the co-ordinates of our route towards Resistance HQ. The overarching narrative follows a similar trajectory to the Danny Boyle film from which the game takes its name, and as we set out at dusk, baulking at every passing jogger, there's suddenly a cinematic quality about everything; I momentarily wonder which of us is the easy meat who gets killed in the first five minutes, then realise it's probably me.
The encounters with the survivors, among them a frightened old man on the doorstep of a terraced house and a diabetic girl trading her knowledge for sweets, are dramatic vignettes in the style of immersive theatre, and throughout there's a strong imprint of collective first-person shooters such as Doom and stealth computer games such as Metal Gear Solid. As such, 2.8 represents a particularly spectacular example of the burgeoning trend for street games that has seen adults in cities around the world reclaiming play of all kinds in public spaces.
The game's sellout three-night run in Leeds last weekend was 2.8's third staging. Its previous incarnations provided the star turn at the most recent editions of Bristol's igfest, a four-day celebration of "interesting games" from all over the world, founded in 2008 by SlingShot, the company behind 2.8. At the end of this month, in a refreshing inversion of the principle that those living within the M25 get everything first, 2.8 will make its London debut. Outings in other cities are planned and will respond partly to demand; thanks to largely word-of-mouth publicity, would-be players have been campaigning for their home towns in their thousands.
On the night, it is clear that though the zombie plague is fictional, enthusiasm for the game itself is infectious. As the crowd builds, there's the friendly vibe of a music festival and a carnivalesque atmosphere enhanced by fancy-dress efforts including multiple paratroopers, Apocalypse Now-style renegades accessorising with cigars, a burlesque performer in leotard and fishnets and a man dressed as a butcher, who I later discover just came in his work clothes.
What's notable, however, is that since it's barely 7pm on a work day and there's not a pint of overpriced cider in sight, the palpable energy is built purely on anticipation. And anyone playing "guess the event by the demographic" would have failed miserably, because there isn't one; although a large contingent is in their twenties, plenty are in their thirties and forties and though there are more men than women, I'd expected the gender bias to be more pronounced.
In part, the mass appeal is down to the undead factor. Zombies have long held a peculiar privilege in the collective imagination, but what with Brad Pitt currently filming post-apocalyptic horror World War Z and the Golden Globe-nominated recent TV series The Walking Dead, they are enjoying a cultural purple patch. Accordingly, there's a good number of self-confessed zombie enthusiasts in attendance – but the rest are here for less obvious reasons.
When I meet SlingShot creative directors Simon Evans, 48, and Simon Johnson, 36, at their Bristol HQ ahead of the event, I quiz them on the secret to coaxing adults not only into sidelining their superegos and yielding to the basic pleasure of playing games, but to doing so in public with strangers. "The proposition has to be outlandish, something people can't believe you're really going to do. That's the draw," explains Johnson. "Then, in the case of 2.8, it's a big production number. We have trailer videos, a slick website; it's explicitly made for grown-ups. You have to be 18 to play our games, not just because of the legal issues, but because adults won't join in if they think it's for kids. They don't want to be infantilised."
Outlandish though the final result might indeed be, 2.8 was inspired by real-life. "When the Tories got in last year, I had a flashback to the 1980s, when everything was basically terrible – transport, education, health service," recalls Evans. "So I wanted to do something about massive social breakdown." Johnson suggested zombies as the quintessential emblem of civilisation in free fall and with the help of artist Hazel Grian, they set about developing the game.
Not surprisingly, their toughest crowds have been, initially at least, the various authorities whose permission is required to stage such an event. "People are sceptical at first," says Evans. "We've had mountains of paperwork to climb. But now they love it." So much so that Bristol City Council now part-funds igfest, cannily recognising both a potential draw for tourists and a conspicuous display of the city's status as a creative hub. And despite the unrest across the UK in August, local support for the Leeds and London events was undamaged.
Although 2.8 is their biggest game, SlingShot's repertoire extends beyond contagion and catastrophe. Moosehunt, for example, takes players on a supremely silly walking safari through the countryside, where they are tasked with producing photographic evidence of an errant moose – or rather an errant man in a moose costume – proving that the human imagination can generate suspense from the most absurd or benign of scenarios.
Meanwhile, Hounded, which hits London's Soho for one night in November, challenges participants to navigate the city by nose as they follow trails laid using scented markers attached to lampposts. The catch is that hot on their heels are huntsmen – in full regalia and with real hounds – tracking the scent that's sprayed on the soles of players' shoes at the starting line.
Both Johnson and Evans come from an arts background, and anyone so inclined can join the historical dots between the street-game movement and the participatory art of Situationism or Dada. But although they see games as an important medium for thinking through social relations and questioning our environments, they're adamant that play needs to engage our sense of fun before our intellect.
"Challenging live-art performance is all right in a gallery," says Evans. "But I don't think you want that on a night out with your mates. You can model a game for fear, but ultimately we want it to be an affirming, progressive social experience. We're not dabbling in the dark side."
The end-point of 2.8 Hours Later Leeds, Resistance HQ, is a Victorian mill housing a zombie disco complete with bar and barbecue. Bouncers in decontamination suits check players' hands for the tell-tale UV cross. The "infected" get a gory zombie make-over, while it's a victory photo for "survivors" – the split is about 70:30. Evans and Johnson have already emphasised the bonding effect of adrenalised shared experiences, but I can see for myself that there's a lot of serotonin in the room tonight. After a couple of drinks and much swapping of zombie anecdotes, everyone departs looking happy and ready for bed.
The next morning as I head for Leeds train station, I'm surprised by how an experience of a city can be so radically altered by suggestion and mise-en-scène – today the streets and malls have slipped back into their anodyne everyday functions. Has it left any lasting effects? Well, there's definitely a part of me that can't help thinking that, should the zombie apocalypse arrive for real, I'll be ready...
2.8 Hours Later is in London from 27-29 October (2.8hourslater.com, see a trailer at independent.co.uk/2.8hourslater). Hounded is in London on 11 November (sohotheatre.com)