At GDC, there is a tech demo from Nintendo Software Technology of Mario vs. Donkey Kong for Wii U using Nintendo Web Framework. I had a chance to try it out very briefly and the controls are on the Wii U GamePad. You can build bridges by drawing a line at the red squares or get rid of bridge a by tapping on them.
You can see a couple of quick photographs of the setup that we snapped below. One of them includes the game code running on a monitor, visible for all to see. Nintendo’s Damon Baker shared with us that the tech demo is simply meant to be that, and is not planned to be an actual game.