App of the living dead - Kim Harrington

Bex, Charlie, and their friends have already saved their town from monsters and aliens - and they've learned their lesson about apps from Veratrum Games Corp. So when the company releases their newest title, a zombie game, the friends band together and refuse to play, even though it looks like the coolest game ever and everyone in town is hooked. Then, when a flu works its way through school, turning students and teachers into walkers of the undead, Bex, Charlie and a few others are immune, because they were the only ones who didn't play the game. But now they have to learn it -
and fast - to save their friends and neighbours - and stop Veratrum from unleashing more of their deadly games!