I spent an hour or so playing A Boy And His Blob for the Wii for this preview, and word that springs to mind is "adorable." This is the kind of game the Wii was designed for.
A reboot of the 1989 NES game with the same name, Blob tells the story of a young boy who helps a white outer-space schmoo travel to his home planet. You do this by feeding the Blob jelly-beans that transform him into different useful object, so if you need to travel up to a high platform, drop a yellow bean, and Blob will transform into a ladder, or a hole in the floor, or a bowling ball, or a rocket, or a bowling ball, etc. etc. The titular Boy is all but helpless without his friend, and the Blob has no direction without the boy's help -- so the two rely on each other to overcome obstacles and fight enemies.