zombies-runZombies, Run! is one of the most inventive games to have been released for smartphones in recent time: a fitness app that encourages players to run with a storyline based on slavering zombies chasing them.

Developer Six to Start says the app has sold more than 300k copies on iOS, Android and Windows Phone – impressive considering it’s a paid app that’s never been cheaper than $1.99. Now it’s getting an episodic ‘second season’.

Pocket Gamer has the details: “The entire Zombies, Run! community will be able to experience the story together, with all the discussion, analysis, and speculation (and official podcasts) that comes with it,” says the developer.

The second season – interesting use of TV lingo there – will be delivered as an update to the first game, with seven missions available for free, and 50+ more available through in-app purchases.

According to the article, iOS will get the second season first, but Six to Start is working to ensure Android is close behind.

The developer co-created Zombies, Run! with author Naomi Alderman, raising just under $73k on crowdfunding site Kickstarter back in October 2011 to make it. It thus sits in a fascinating spot between games, fitness apps and fiction, now with TV-style episodic content being added into the mix.