Well I downloaded the app (£2.49) and off we went. I can't be bothered with instructions so I chose to run 5k as opposed to stopping when I completed a mission (I think!?) which was at just over 4k. When it comes to running away from the zombies I tried my best but they unfortunately caught me three times - at least I tried to sprint away and I got lots of supplies.
So I did my 5k in less than 35 minutes and we have decided to mix our runs up to include a 5k consisting of purely hill training, another to do sprints of 100 metres followed by walking for 100 metres, Zombies and then a flat, straight run of 5k to check our PR.
Can't believe I'm enjoying this - also lucky that I've managed to get a group of four who can run together three times a week.