For all of the technical wizardry going on behind the scenes, Left 4 Dead was a simple game: four players versus seemingly endless hordes of zombies, peppered with the occasional, amped-up special zombie. Evolve, the latest game from Left 4 Dead developer Turtle Rock Studios, trims down the number of bodies on screen while simultaneously introducing new layers of complexity. Evolve ditches the undead hordes for a single, player-controlled monster pitted against four player-controlled hunters. On the surface, it's a much simpler formula, until you realize that each hunter has their own individual set of weapons, items and abilities, and the monster is constantly evolving, steadily becoming stronger and more deadly as the round progresses. (You'll find our video preview from February after the break, if you want a better idea of how it all works.)

After trying my hand as the monster at PAX East - and losing, sadly - my first question to Executive Producer Denby Grace was obvious: How do you balance this? How do you make sure it's both fair and fun?

"There's just a bazillion little dials that we can twist," he says. "The biggest thing we do is we playtest a lot. We have a huge telemetry system built into it." Every match that Turtle Rock plays internally, whether by the development team or QA, brings with it lots of data, he says. "Every ability, every item, every weapon has its counter as well, on the opposing team. In that respect, we're very careful about not giving people a bunch of overpowered stuff. It's a real precision exercise, and it only comes out with playtesting, so we do a lot of it." Everyone in the studio, he says, plays around two hours of Evolve every day.