Welcome to Kixeye. You'll never find a more wretched hive of scum and villainy," snarls the virtual receptionist when you ding the bell on a visit to the homepage of the social gaming company's website. She's a tough cookie, barely raising an eyebrow as a man engulfed in flames runs screaming past the front desk.
Arriving at Kixeye's real-life reception in a San Francisco office block, I expect the experience to be less menacing â€“ without the virtual glass cabinets stuffed with weapons, for instance. But, emerging from the lift, I hear an ominous rumbling noise and step out into a corridor lit dimly by red lights. At the end is a security guard in full camouflage gear, a Glock .45 calibre pistol in his gunbelt, who checks my name before allowing me into Kixeye's inner sanctum.
The gun was real, Will Harbin, chief executive and founder, confirms. "We have very passionate users, we had a couple of visitors at our old offices who turned up wanting to talk to somebody and that made us nervous," he says. "You have to wonder about the psychological profile of someone who hops on a flight and travels thousands of miles just to talk to you."
Kixeye develops massively multiplayer online games and he recalls a story of a Chinese fan of one MMO who was killed in real life for selling a virtual sword he had borrowed.
Fans of Kixeye games are hooked on its three multiplayer strategy games on Facebook: Backyard Monsters, Battle Pirates and War Commander, which let players build empires and battle with friends. The latter two games are among the top grossing on Facebook, despite having only a fraction of the players of the kinds of games developed by Zynga, the leading social gaming company on Facebook.
"Kixeye's big accomplishment is it has proved you don't have to be developing the stereotypical Ville-style game [created by Zynga] to be hugely successful on Facebook," says Mike Thompson, lead writer on the website Inside Social Games.
The ambience of Kixeye's themed office space is meant to be something between an evil spaceship or the underground bunker of a secret government installation.
This is very different from the headquarters â€“ in a trendier part of town â€“ of Zynga, developer of games such as Farmville or Cityville in which players harvest crops, build cities and complete puzzles. There, you arrive at a "shack" modelled on the company's FrontierVille and mix with staff and their dogs in an amusement-park style atrium.
The 35-year-old Mr Harbin also strikes a deliberately more serious, conventional-business pose than Mark Pincus, Zynga founder and CEO, a T-shirt and jeans man . The Kixeye CEO is wearing a smart pale jacket with a neat handkerchief in the breast pocket, while a bottle of Macallan single-malt whisky stands on the drinks tray, rather than the usual start-up health drinks.
In fact, Zynga and Kixeye are "100 per cent polar opposites", says Mr Harbin, keen to present Kixeye as a more serious company â€“ perhaps the sort that, if this were a video game, becomes the eventual nemesis of a bigger rival. "Zynga definitely tries to dumb down the experience," he continues. Their motto is games that your grandmother would understand. We don't want grandmothers or even mothers playing our games."
Less than 3 per cent of Zynga players spend real money on virtual goods, but Kixeye claims far higher percentages thanks to its very dedicated, predominantly male, players.
Mr Harbin's championing of two-and-a-half-year-old Kixeye marks a return to his first love. He began coding in kindergarten at the age of six on Apple II computers and developed games at high school and while studying computer science at university. But his efforts failed to win interest from videogaming companies.
He abandoned games, eventually ending up in San Francisco six years ago to join Affinity Labs, an online professional community-builder bought by Monster, the recruitment site, for $60m little more than a year after launch.
Mr Harbin stayed for two years before being tempted to focus on games again â€“ specifically, the opportunities offered by one booming social network: "The games I saw on Facebook were all junk. They were certainly not targeted towards males, so I was on a quest to figure out how to start a game company." But it was not easy. "Frankly, I had zero clout in the game industry and I couldn't find any good developers to start a company."
Then he met Dave Scott and Paul Preece, who had started Casual Collective a studio that was making no progress as a business. "They needed leadership and direction, so we decided to join forces and form Kixeye," he says matter of factly.
This year, the start-up expects to record revenues of more than $100m. While that is small compared with the $1.2bn that Zynga hopes to achieve, the hardcore gamers attracted to Kixeye's Facebook games spend at 20 to 40 times the rate of Zynga's casual gamers, claims Mr Harbin.
Kixeye's promising outlook, he adds, comes from its focus on building teams who are skilled in MMO and real-time strategy (RTS) games. He says these are truly social games because of the way players can chat and compete with each other onscreen while inside Facebook, rather than sending alerts and gifts of virtual goods in Facebook news feeds.
The original team of three has reached 250, with Kixeye hiring about 20 people a month. "We haven't had a miss, we're very excited about the games we're making and this is a child's dream come true," he says, the mask of hard-headed businessman slipping a little.
Kixeye has had $22m in backing from Lightspeed Venture Partners and Trinity Ventures and is profitable. Despite its affirmation for Facebook, it plans to launch its own, separate platform and to release higher-quality 3D games â€“ moves that will put it in competition with bigger rivals in Europe and Asia such as Bigpoint, Nexon and Sony.
While Kixeye's games are all free to play, users can pay to fast-forward to higher levels. But the game is carefully calibrated so that those willing to spend the most money don't necessarily win. Mr Harbin counts himself among this latter group, playing two to three hours a day and acting as chief game tester and product officer.
On the way out, he pauses in the gloomy antechamber, under the company's motto carved in fake stone: "Innovation over imitation, quality over quantity, passion over profit." The setting seems like part of a role-playing game, but Kixeye's rapid, real-life success has the industry taking it ever more seriously.