Most of the video game Twitterverse will remember the slow motion, reverse teaser trailer for, Deep Silver and Techland's open world zombie game. It was the toast of Twitter and drove the game from total obscurity to most-wanted for a huge number of players.It wasn't the key to the game's success, however, argues executive producer Guido Eickmeyer, who works at publisher Deep Silver."Unfortunately, it doesn't work that way," he says. You can't rely on a great trailer and expect success.In the end, the game sold 4 million units -- and it didn't sell them "in one month, which is not really possible," he said. "We sold them over a long time. It was a continuous sales curve."In fact, he says, there was a crucial point in's development where the team sat down with the game in progress, and tried to figure out how to turn it into a success."We found it wasn't heading in the right direction, so internally, we as team sat down and thought about what we can deliver. How can we make something out of this game?"At that juncture,had "some very good ideas, and some ideas at that point which were not really great." The key was to figure out which were which and head toward the good ideas that were actually achievable.For example, he kept hearing "nowadays, story is the thing -- story and characters. People were insisting we have to go on that direction -- we have to have a game like the trailer," says Eickmeyer.The problem, however, was that "doing scripted story games requires a ton of money," he says -- something Techland didn't have. "Our answer was, well, no. We don't have to, because our resources can't do it," says Eickmeyer. "We can't do a game like the trailer."Instead, the team evaluated what worked about the game in progress and what skills the team at Techland had, and decided to emphasize the co-op gameplay. This, Eickmeyer believes, is what drove the ultimate success of the game and its long sales curve."This is why people are buying it months later; this is why people love the game; this is why we have great reviews from users," he says. "It is the most exciting co-op experience that is on the market."According to Eickmeyer, players ofhave racked up 6,500 years of co-op play so far. "This game was co-op, totally co-op dedicated," he says. "We found we need to focus totally, and this is what we focused on."You work on the things you are very good at and improve them," he says. When the team sat down to evaluate the game, "what we had at this point was already a sound multiplayer system," which dictated how to move forward."We won against competition with huge budgets," says Eickmeyer. "We beat the guys with the big money and with a lot of experience.""If you have some talents, work on those talents -- don't try to put them in a direction or a system they don't flourish in," he says. He believes that if he had pushed Techland toward making a story-driven game,would never have worked -- because what story is there is "cheesy," and the multiplayer expertise of the developer was brought to the fore instead."Take what you have as resources, and try to make something like that, rather than trying to have some overarching idea that you're not going to make anything with," he says.