Described as 'the first location-based mobile game', Tron Lightcycle also happens to be free. Which is always nice to hear.It's a joint affair between fizzy pop company Coke and movie house Disney, tracking the GPS on your iPhone to imitate a Tron Lightcycle's light trail. The idea is to 'trap' other people and force them to crash into your wall, picking up points as you do it.According to TechRadar, there's a speed limit involved, where the Lightcycle on your phone will 'discharge' if you're going too fast. So no jumping in a car or getitng on a real cycle to cover space more quickly.It sounds like a lot of fun, but also just a tad confusing. But it should liven up a dull afternoon's walk. Just make sure you don't get run over as you create your nice shapes. Find out for yourself right now if you have an iPhone, with an Android version following soon. Still confused? Check out this video of it in action.