An explanation on Peer to Peer Scoreboards
Some people have asked how the scoreboards in our game works. XBLIGs cannot use a server to deal with a list of scores, so instead they used a peer to peer system to exchange and propagate scores. Since it’s a bit special here is an explanation.
When you are playing the game you automatically connect to other players that are also playing at the same time. Once connected together players echange their scoreboards and get new scores that they didn’t have before. This is how scores propagates. So if you and your friend want to exchange scores, make sure you play at the same time for a few minutes, and voila you both have the same updated scoreboard.
Note: You need to have a gold account to send and receive scores, because connecting to other players uses the XBox Live network.