Zombies, Run! turns a boring run into an exciting chase with zombies. The app puts together a whole narrative while you're running while at the same time tracking your stats and ensuring a good workout.
Despite the fact that Zombies, Run! is not ranked in Apple's "Top Free Apps - Health & Fitness" genre, the app garnered $15,315 in revenue in June from Apple's App Store, according to AppData. Unlike most of the apps in this list, Zombies, Run! is not free, so you'll have to shell out $3.99 to have zombies chase you.