This sense of embodiment could easily have been frustrating – we’re used to instant and constant run speeds in games, rather than having to labour to build up momentum. But the emphasis Mirror’s Edge places on the physical exists simply to enable your athleticism, rather than to hinder it – allowing the player to perform stunts of grace and energy that would have felt clumsy were the player’s agency more abstracted from the environment.

“A lot of the moves you do are parkour moves,” says O’Brien. “We decided fairly early on in development that we wanted to do a game that was based in an urban environment, positioning it away from military and war and the big open spaces of Battlefield. We started off prototyping in Battlefield 2, and we found that one of the things we wanted to do we couldn’t, which was to move around the city on foot – we found that vehicles were quickly abandoned. In the narrow city streets people drove them for ten yards, jumped out of them again and ducked down an alley, or ran up stairs or ran into the subways. We’ve got a very vertical world, and found that people wanted to move around that quickly on foot.”

The result is fluid acrobatic movement – a continuing string of elegant wall-runs, leaps, vaults and the like that turns the urban environment of vertiginous walkways and roofs into an elaborate assault course.

“This is going to sound like typical developer hyperbole,” says O’Brien apologetically, “but when you play this game for a while it changes the way you look at levels in other firstperson games. You stop seeing obstacles and start seeing opportunities: ‘I could wall-run up there and jump there and do this and that’. Even on a very small rooftop everyone approaches it differently.”

“Doing the cool moves is relatively easy,” explains Farrer, “but you want to maintain a flow – that’s where the skill element is introduced. Coming to the bottom of the zip-line you want to time your landing properly so you can continue to maintain that speed and carry on moving, whereas if you fail you may stumble, slow down or even fall over.”

moscallout“When you play this game it changes the way you look at other firstperson games. You stop seeing obstacles and start seeing opportunities”/moscalloutSimilarly, when approaching a metre-high wall – which in other firstperson games might be an impassable structure – the velocity with which you hit it will enable you to vault straight over or, failing that, leave you hanging. Maintaining speed via fluid combinations of moves is the central tenet of the gameplay. Your average speed also determines the amount of Reaction Time you have, a slow-motion feature implemented to aid you in the more complex and rapidly chained moves. Although perhaps more obviously a gimmick than the game’s other integrated notions concerning movement, it is certainly of some considerable benefit during the more hectic moments; when you launch yourself from the edge of a building and spin in mid-air to shoot back over your flying body at your pursuers, Reaction Time gives you a few critical moments to get a bead on your foes before you slam in to the ground.

“Aside from just considering how this was all possible technically,” says Farrer, “we spent a lot of time thinking about what you’d be doing with the controller. We want to keep control of movement off the face buttons, because the second you use a face button you move your thumb off the analogue stick and you lose control of your aiming.”

Although still undergoing development, the controls have been streamlined in other ways. There is no ‘grab’ button as such: the game uses a complex edge-detection system to allow you to automatically gain purchase on ledges. Only two buttons determine your context-sensitive actions. The jump button becomes an all-purpose movement button, executing vaulting manoeuvres as well as repelling yourself off adjacent walls. An ‘aggression’ button not only shoots, but allows you to barge down doors while moving at speed, or kick them open if standing still.

Combat maintains the focus on motion, as Farrer explains: “Your enemies are powerful and heavily armoured. They’re dangerous – your pistol isn’t going to do much damage to them. So what we wanted to do is to infuse movement into the combat – firstly in avoiding your enemies; the more acrobatically you navigate the world, the harder a target you become.

“Alternatively you can get in close to them and turn their own weapons against them; snatching a weapon from them and using this more powerful gun to dispatch the harder enemies. We look at these larger weapons as temporary power-ups, because once you take them you’re limiting your mobility but increasing your power. It’s an interesting trade-off. You can’t carry around an enormous assault rifle while you’re doing these athletic stunts.”

The game clearly isn’t about dispatching endless thousands of bad guys, however – your enemies represent a real threat, and one that, for the most part, you must outrun rather than outgun. “One of the conventions we were interested in breaking was never putting enemies behind you,” says Farrer. “Other firstperson games often have you moving towards your enemy, and clearing the threat. We wanted to give this idea of chase. The enemies aren’t there for cannon fodder; they’re frightening and powerful.”

“And you’re always chased by a horde of them,” continues O’Brien. “You’re  outnumbered – there’s no doubt that you need to be running.”

This central premise of continuous acrobatic movement wouldn’t work if the environments weren’t designed to encourage and direct it. Yet, at the same time, the urban setting must remain convincing, necessitating a delicate balance between giving an impression of openness to the rooftop world, and making sure the player doesn’t continually plummet to the tarmac far below. It’s a balance made possible by the art direction the team is pursuing, one that is perhaps even bolder than its innovations in firstperson movement. It’s an art direction that directly informs the gameplay while at the same time creating a vivid sense of the unique and intelligent backstory.

“Your character, Faith, has a Jason Bourne-style sense of potential escape routes,” explains O’Brien.

“We wanted to get that feel into the game, seeing the world as a she would see it; stripping out everything except that which would be important to her. We want the player to move through the world very quickly, and we want the player to know what their options are. All the things that are important to you will pop out.”