Woe betide the developer who creates a first-person shooter with potential grand scope for expansion on the theme -- or otherwise -- and ignores the modding community. That's the message that Bohemia Interactive, the studio behind 2009's Arma 2, is shouting from the rooftops. The team has always seen modding tools as a huge part of its releases, but over the past few weeks, this point has really been driven home, thanks to the release of DayZ, a zombie mod for Arma 2 that has given the title an unprecedented boost in sales. DayZ puts you in the midst of a wide-spreading infection, that has turned the majority of your fellow humans into zombies. The brutal mod asks you to stay alive as long as possible, as you try to steer clear of the undead and bandits, while also keeping your energy up and scavenging for food and supplies. The alpha release has seen sales of Arma 2 skyrocket, and the game has been on top of the Steam best-selling charts for a good week, three years after the original release. "The uplift is very significant on Steam," Bohemia's Marek Spanel told Gamasutra. "If things continue going in this current direction we may be looking at a tenfold increase in Arma 2 sales there over the previous month." "Our Arma series has grown up around the user modding community since the very first PC demo version was released 11 years ago," he continues. "Modding is and always was, essential to Bohemia Interactive's work, sometimes even more important than completely polishing the built-in content in our titles. Without our users Arma would never be what it is now." Similar can be said about such big-name franchises as Half-Life, Unreal and Mount & Blade, he notes. "I believe modding simply is an integral part of the PC gaming scene and I doubt this comes as a surprise to any PC developer." "It's one of the greatest things on the PC as a platform and a reason why I prefer PC over the more closed proprietary platforms, not only as a developer but with quite rare exceptions also as a gamer." The Arma 2 team has met up with the small outfit behind the mod to discuss the future of the mod, and plans to do so again soon -- although Spanel notes that there are currently no plans for Day Z to be integrated into Arma 2 as an official mode. "Arma 2 is not really about survival and fighting infected opponents, so directly integrating DayZ may not be fitting into what is on the whole a more serious military game, even if DayZ is a prime example of many of Arma 2's strengths," he told us. "I can't speak on behalf of DayZ mod's developers, but from my perspective there are some very important issues to be addressed in core Arma 2 baseline first before it makes sense to try to think ahead," he continues. "Or is it because I don’t really enjoy falling from ladders in Chernarus as much as I did in the early days of Arma 2?" Dean "Rocket" Hall, one of the devs behind the mod, explained to Gamasutra that he chose to mod Arma 2 for numerous reasons -- the foremost being his interest in the use of games for training purposes. "[Arma 2's Real Virtuality engine] focused on many of the areas I am very interested in, being authenticity with experience - rather than strict gameplay balancing or realism," he noted. "They're very different things, realism and authenticity. I wanted something that allowed me to place players in situations that would really force them to make decisions and get their thought processes going." Given the popularity of the mod, and the spiralling sales of Arma 2 as a result, what does Hall believe this says about the importance of mods in modern gaming? "I think that when someone says that modding is a declining trend, what they really mean, is that they hope its declining," he suggests. "I think that video gamers are much smarter than most companies give them credit for, and now through social networking they can really give the big companies a run for their money as they are connected more than every before. I think big companies have seen social media as a great marketing tool, but some don't realize that it spreads bad news at least as fast as good news." He continues, "This means that as game designers we need to be providing good products, because it's harder to fool the customers simply by getting a few good reviews from sympathetic websites." Hall urges players to "vote with their money," and show developers what's really important in games through sales. "That's what the studios notice, the bottom line," he notes. "Not many mods get the chance to really send a message to the game's creators by putting them into the top sellers, but this mod has had that opportunity and it's gotten people's attention. Customers need to make sure they're sending this kind of message more often, and social media now makes this possible like never before."