Well, I've never actually used dropbox, but I've set up multiplayer on my home network, which uses the same system. But, I'll let someone else explain how to get the dropbox part working. Not sure if you've come across this, but you can make an online score table like this.
http://game-editor.com/forum/viewtopic.php?f=6&t=10459Essentially though, what using dropbox does, is allow multiple users to play the game from the same place (with a delay). That way when you use saveVars, the other player can use loadVars on the file you just saved. So, both games are saving their relevant information (such as positions, animations, and similar), and then loading the other player's save files. Setting up a hiscore table is pretty similar, but you have to watch out for two people trying to save a new hiscore at the same time, which then you'd need a lock system.