It looks like Mr. Game & Watch's head. The back of Mario's hat looks like his nose.
Whether that's intention or not, who knows.
There's a picture of Zelda Wii U hidden in the 40th pixel from the left.
It's shaped like game & watch's head facing the right.
Ohhhh, I see it now. Could this be hinting at the NX being the long-coming revival of the Game and Watch brand?