I just wanna say why i suggested this.
We have all received the message from our mate dave on facebook saying "Dave needs help fighting off the evil monsters in monster fight madness join up to help him in his fight". Bush dosnt have this so this would be a way for people to invite mates and gain a small extra income from new players who stick around. rather than the current method relying on your invites buying bc if that still works like taht.
but what about those who don't have a facebook (or any social network sites') account? bush is actually going to promote facebook as a result? :< i think the rewarding system that directly influences players' score shouldn't depend on this aspect.
+1
also not forgetting those who have facebook but don't want to attach the game to their facebook account.