I would like to create a mobile game (iOS and Android) that has location-based and augmented reality features.
The idea of the game is to navigate through a city or a location and search for a virtual wall (defined in different fixed locations) that is only visible on the mobile. Once found, the player can leave a message (or image) on the wall and get some points and other incentives for doing so. If another player finds the same wall, he will be able to see all the available message (from other players) and leave a message as well and continue looking for another wall.
That's the general idea behind the game.
To recap: Walk - find a wall - message - get some points - find another wall - message - etc...