This is something that I hope Microsoft standardizes with future updates, but right now most games do not have cloud saves. Some do, like Skulls of the Shogun, Halo: Spartan Assault, etc., but most do not. Instead, save data is stored locally on the phone, within the app itself (i.e., you cannot even back it up to a different spot on your phone). So, if you have to reset your phone, or if you uninstall and reinstall a game, all your saved game progress is lost! So, be careful and don't uninstall games unless you really want to or have to. I had Xbox support tell me to uninstall a game (because the guy didn't know what he was talking about as he assumed Xbox games on Windows Phone were the same as those on Xbox 360, which have cloud saves or separate save files locally). I did what he said and lost all my save progress for Carcassonne.