Multiplayer, particularly the online variety, is practically a must-have feature for any type of game nowadays, as lots of players want to experience their favorite games with others, either cooperatively, like in Mass Effect 3, or competitively, like in FIFA 13.
There are quite a few games that didn't feature any sort of multiplayer mode, like Dishonored, but there are others that tried to balance things out, either by ingenious solutions, like Hitman: Absolution's Contracts mode, either by implementing old-school systems like local multiplayer.
The first Nintendo Wii U games take this traditional route, as they focus on playing with others locally, not online.
Both titles made by Nintendo, like Nintendo Land and New Super Mario Bros. U, as well as ones made by Ubisoft, like ZombiU or Rayman Legends, have such an emphasis.
Nintendo's developers even confessed that they had tried to get players to experience gaming on the Wii U with others in the same room because Nintendo Land's lack of online connectivity.
Other games follow this same strategy, as both New Super Mario Bros. U and Rayman Legends, two great puzzle platformers, rely on someone using the Wii U's GamePad to help the actual characters who are jumping through the level.
The Mario title lets GamePad wielders to create new platforms for their friends (who play via the Wii Remotes), while Rayman puts players in the flying shoes of Murphy, a new character who can manipulate platforms as well as enemies and the environment.
Last but not least, as we highlighted in our review, ZombiU has just a local competitive mode, in which the GamePad user is the king of the zombies and must impede the efforts of several survivors, who are controlled by other people by using the Wii Remote + Nunchuk or the Wii U Pro Controller.
This whole emphasis, while a bit awkward considering how much people tend to play online, it does get people to experience playing on the Wii U, even if they didn't buy a console and will make them more likely to consider purchasing one.