Couldn't you use physical QR code stickers for such proof of location? They can be fairly small and merely need to contain a random UID code (or an URL with the code as query parameter).
Of course that only works up until people start sharing those codes online, even though you can tweak game mechanics to discourage players wanting to do that, it's impossible to prevent.
Precisely. Which is why I think this will have a tough time succeeding. Even casual gamers will eventually get frustrated. This is also the sort of thing that is difficult to repair once the damage is done.
Of course that only works up until people start sharing those codes online, even though you can tweak game mechanics to discourage players wanting to do that, it's impossible to prevent.