The idea was to do an animated video using a series of pieces of toast; it's much like a flip book, except the images are dark outlines made by laying a stencil over a piece of toast and torching it until the image is dark. (darcypattison.com)
As you can see from the trailer they have matched the cartoonish art style that was used for Super Smash Bros. for 3DS including the distinct dark outlines. (engagedfamilygaming.com)
Exuberant boyhood incipiently aware of the possibility of ridicule is suggested, but lest things get sentimental, the too - dark outlines scrawled around his fingers and teeth amuse. (painters-table.com)