The comic-book writer Kieron Gillen once described games journalism as travel journalism about imaginary places. This captures the role of the player, too: you're a temporary resident enjoying new locales, cultures and, more often than not, greatly relaxed health-and-safety guidelines. It's not surprising that many of the destinations in games are cities. Varied architecture delivers the playground and the colliding motivations of city-dwellers and the player drive the narrative.
For those seeking heady thrills, cities often have the obvious benefit of being tall. Manhattan has offered drama for performers ranging from Gene Kelly to King Kong. No wonder Spider-Man's adventures on the Norfolk Broads were so unpopular with fans. Game cities also have their own complex systems (early editions of SimCity taught many of us that roads don't curve and, thanks to Grand Theft Auto: San Andreas, gamers now know that most pimps aren't white).
In recent years, there have been more concerted efforts to reconstruct real locations, partly because processing power in modern computing has been up to attempting facsimile - but there are also more practical motivations. A designer on the Project Gotham Racing series, in which players race cars around the carefully re-created streets of famous cities, once remarked to me that one of the main reasons they went to the effort of photographing every square inch of a route in order to rebuild it was that it was much easier than trying to imagine a new one. As he succinctly put it, "Cities are really complicated."
It's remarkable how little detail is required to feel a resonant connection with the simulation of a real place. Treyarch's Spider-Man 2 gives us the loosest approximation of New York City, built entirely from low-fidelity grey blocks. Yet, with the proportions roughly correct, Central Park reduced to a patch of green in the right place and the Flatiron being just wedge-shaped enough to be recognisable, the sensation of moving through Manhattan is achieved.
And so to Assassin's Creed: Brotherhood, a game about cities. For those unfamiliar with the conceit, the series places you in the role of Desmond, an unsuspecting, 25-year-old bartender. Kidnapped by a shadowy mega-corp (a front for the Knights Templar, no less), he is placed into an "Animus" machine, which allows him to relive the memories of his ancestors. In a wise decision by the writers, Desmond's forefathers didn't also work in hospitality but were skilled assassins from the 15th century. So far, so much fun-but-impenetrable hokum - until the location for your adventure erupts on to your screen. Suddenly, you are the charismatic killer Ezio Auditore, stalking a bustling Renaissance Rome.
You traverse the world primarily using the recognised 15th-century street skill of "parkour", in which you find yourself to be more than a little proficient. Run at any building with the "free-run" button depressed and Ezio will gracefully climb its face, grappling on to ledges and swinging around flagpoles with exceptional ease. It's a generous illusion - Ezio ascends with flowing, uninterrupted animation - empowering you with great skills but without making you work for them. The highest points in Roman architectural history are yours to explore and leap between.
Within the game, your work builds on the activities that you performed in the prequels, moving through crowds and over rooftops in order to assassinate your foes silently and reduce the Borgia influence within Rome. The labyrinthine plot runs in parallel with your adventures, shoring up its historical pedigree with cameo appearances from Machiavelli, Leonardo Da Vinci and Lucrezia Borgia. But, for this player, tracking its convolutions was too much effort.
It's a mature, complex and artfully delivered narrative - but when it's so easy to explore this amazing city, trying to remember why you're ascending the Colosseum seems a chore compared to doing it. Sometimes, it's just better to be a tourist.