Forget your Guitar Heroes, your Rock Bands and your Rocksmiths -- playing guitars, drums and keyboards to music in games is so last decade. The cello is where it's really at. Cello Fortress is a work-in-progress by Proun developer and Ronimo designer Joost van Dongen, and as far as I'm aware, it's the first video game to incorporate a classical music instrument (feel free to correct me if I'm wrong!) into the gameplay. The game will first be shown at the Dutch Game Garden Indigo exhibition later this month. Cello Fortress isn't simply a video game, however, but rather an interactive music concert. An audience will watch as van Dongen, on his cello, attempts to play improvized cello pieces while simultaneously fending off attacks from players who are controlling tanks in a bid to destroy his castle. "I play cello and my music is analyzed by the game [via a microphone]," he explains to Gamasutra. "The game has certain rules for what controls what, and can recognise the difference between aggressive music, slow melodies, high or low notes, those kinds of things." For example, if van Dongen plays a certain melody, the game will pick up on this and a bombardment will begin on-screen. Aggressive chords, on the other hand, will equip him with flamethrowers. Other attacks include machineguns, homing missiles, and a walker that strides out of the castle and attacks players. All these attacks are produced depending on which piece of music the cello is playing. "The link between cello and game is very direct, while at the same time leaving me enough room to improvise music that actually sounds good," he adds. "That's a complex challenge, because music needs to flow in a certain way and cannot instantly switch between all kinds of styles and sounds." What makes Cello Fortress even more interesting is the fact that van Dongen isn't looking to "beat" the players as such. While the audience's goal is clear cut, his task is more to make sure he is always entertaining the crowd. "I have to put up a good challenge for the players, while also making sure the music is fun to listen to," he says. "A single play session will probably last something like five minutes, so that as many people as possible can actually play. So it is a short and simple game: people need to be able to pick up the controller and play immediately." The concept, which van Dongen put together via his love for programming and playing the cello, is still in its infancy, and the creator wants to see how it fares in public before he decides what to do with it next. "Live music improvisation to control a game is such a weird and innovative concept, that I really need to experience it myself to be able to know where I might take this next," he says. He doesn't see it evolving into an entire orchestra versus an audience, however -- "improvised music becomes more difficult with more people," he notes. "Getting five musicians to go into the same direction musically and to really improvise something original is already very difficult. For many people it only works if the music is extremely structured, like in jazz." However, he does believe that having several musicans could potentially work if structured properly. "Instead of a cello solo, this could also be a band thing, where an entire band controls the music," he muses. Visitors to the Indigo exhibition may perhaps see this in action. Cello Fortress is just one of numerous indie titles that have become huge hits at open shows and exhibitions in recent times -- titles like Joust, Nidhogg and Hokra have also captured the imaginations of both players and audiences. "I think the reason for this is not so much that public event gaming is hot, but more that games have recently started diversifying enormously," believes van Dongen. "Gaming has grown up and spread out its wings, and now especially the indie scene is very much into weird experiments and trying new things." Since public gaming events are a relatively new field, it means that developers are able to experiment and come up with completely original and unique ideas in a bid to find what works and what doesn't, he notes, and that's what he aimed to do with Cello Fortress. "I think it is an awesome and interesting idea and I want to try it," he adds of the game. "The nice part is that I don't have to choose between this and more 'normal' games: I can do both. At Ronimo we make downloadable games, and in my spare time I am trying this weird thing called Cello Fortress. Both are exciting to do and I am happy that I can do both at the same time."