
It also means your old Wii saves are incompatible. Nintendo told Kotaku that when you transfer your games from Wii to Wii U, then update to the new Wii U version of the game, you won't be able to use your save file on the Wii U version. For Balloon Fight, that's not such a big deal, but it's important you're aware of that before you try to pick back up in a longer game.

