Platform: iOS, Android; $3.99 

Zombies seem to be all the rage nowadays, and now they've made their way into workout apps. In Zombies, Run!, the screams of the undead will rip through your headphones while an audio story is played during your run; creating the illusion that, uh-oh, you're running from zombies. It's a pretty cool idea. Runners are given orders from the audio story that will urge you to increase the pace, all to make sure you get home alive.