Wish you guys the best of luck! As someone who has worked on and thought about location based gaming like this for a long time but failed to launch I'm really hoping you guys pull it off. We even called our prototype "Turf" :)

Location based gaming throws up a lot of challenges and problems that we felt were less than ideal as a gaming experience and instead of just launching something, we over analysed and try to solve them all upfront (without evidence that they are really problems). My only advice is just launch!