It's like Pac-Man Vs., but you might actually have the equipment to play it!
Pac-Man Vs. was a game that showed off the connectivity between the Game Boy Advance and the GameCube. Chase Mii is a game that shows off the connectivity between Wii Remotes and the Wii U controller. It is also an excellent game of hide and seek.
In the demo, one player, clad in Mario garb, is given a 15-second head start to run away from the other four players. After that, the other four try to capture the Mario-looking Mii.
The catch is that the four seekers are using Wii Remotes to move around while looking at the TV. The runner is using the Wii U controller, and has a bird's-eye view of the mayhem, along with a third-person view of the character on the touch screen.
The experience is a ton of fun, though a little simplistic. It shows that Nintendo really kept the concept of GBA-to-Cube connectivity in mind when they made Wii U, as the resemblance of Chase Mii to Pac-Man Vs. is uncanny. It's also one of my favorite Wii U demos, as the multiplayer is a lot of fun, as long as you have five people to play it.