If the first rule of surviving the zombie apocalypse is cardio, you might as well throw on a pair of running shoes and start getting ready. If that sounds awful, a sentiment I share, perhaps you might feel more inclined with a little undead inspiration from U.K. developer Six to Start. The company's hugely popular smartphone app, "Zombies, Run!," pushes you to walk, jog or run via an audio adventure. So in between your favorite beats, you might hear a voice come on telling you there are five undead on your tail and to pick up the pace.

screenshot of Zombies Run app

Engrossing stories drive the action — and keep your legs pumping — in 'Zombies, Run!' (Photo: Six to Start) 

All of this is tied to what's actually a pretty good story, with the goal to survive out on your real streets, trails, et cetera while avoiding imaginary zombies and picking up virtual supplies for a base back home. It might sound silly, but for people who hate running, it's actually proven to be a rather fun source of motivation. Since it's launch in 2012, it's been purchased more than 1 million times.  If you're one of those who hasn't been willing to part with your cash to give it a try, there's good news: as of today, "Zombies, Run!" is a free-to-play app. 

"We have a great hook: run away from zombies in the real world and get fit," Six to Start boss Adrian Hon told the U.K. Guardian. "But it’s not really easy to convey that on the App Store. What we really need to get people to do is just try it." 

Like other free apps, Six to Start is hoping that the four included story missions will entice you to pay $2.99 a month or $19.99 a year to unlock all 200 additional story missions. Each mission plays out like an episode in a television series — so you're not only getting a great workout, but a fantastic post-apocalyptic zombie story as well. 

"As for the zombie component, I both do, and do not recommend using this for training on foggy mornings, and gloomy evenings," writes Amber Lee on the site BreakingMuscle.com "We’ve had some foggy, rainy weather around here that just screams zombie movie, and I think my running times improved just from the adrenaline!

To give the app a shot, jump here. A promo video for "Zombies, Run!" is below. 

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Michael d'Estries ( @michaeldestries ) covers science, technology, art, and the beautiful, unusual corners of our incredible world.

Exercise app 'Zombies, Run!' now free for the living
Just in time for the apocalypse, one of the best running apps for your smartphone is now free-to-play.