New Super Luigi U

New Super Luigi U (styled as New Super Luigi Bros. U) is an expansion pack to the Wii U title New Super Mario Bros. U, released as part of The Year of Luigi. It features Luigi as player one, with Yellow Toad, Blue Toad, and, notably, Nabbit (who replaces Mario from the original game) playable in multiplayer mode. Features like Challenge Mode and Boost Rush are not available.

The title was released for the Wii U eShop, and can be purchased by accessing it via an Internet connection (a copy of New Super Mario Bros. U is required to download). Once downloaded, the player must select the icon on the top left corner of the file select screen to play. Wii U Pro Controller support is also included in both games in addition to Wii Remote and the Gamepad controls in New Super Mario Bros. U. This game will also be released at retail as a standalone game which will not require New Super Mario Bros. U in order to be playable.

Gameplay
The gameplay is largely similar to its base game, except that the playable characters retain Luigi's higher jump and lower traction from Super Mario Bros.: The Lost Levels. The game itself is also made harder, and every course starts at one-hundred seconds. Elements like Items, Power-Ups, Star Coins, Toad Houses, Enemy Courses, and bosses are retained.

Playable

 * Luigi
 * Yellow Toad
 * Blue Toad
 * Nabbit
 * Mii

Changes
The world map itself is unchanged from New Super Mario Bros. U and level designs have had a drastic makeover, making them much harder. As mentioned above, playable characters and their abilities have changed. The timer for each level is also set to start from 100 seconds and the 100-seconds time bonus are added to the timer after going to the boss door in the towers and castles. Items in red Toad Houses may vary as well. For example, a 1-Up Mushroom is in place of a Super Mushroom. Similarly, Enemy Courses have random power-ups such as Mini Mushrooms and Propeller Mushrooms as opposed to only Stars. There are no Checkpoint Flags. Also, many elements of the game are colored green to emphasize Luigi.

After the game is completed, the Mario Block appears at the beginning of levels. This allows the player to switch to the original game's physics, with lower jumps and better traction. Nabbit is not affected by the block. Nabbit is also playable in single player mode if the player holds down on the / or  on the  while selecting a level. The player's Mii can also be used if the same trick is done on the Flying Squirrel Ovation level in Superstar Road.

Worlds
There are 82 new courses replacing the original courses from New Super Mario Bros. U with different level names, though the world names are retained.
 * Acorn Plains
 * Layer-Cake Desert
 * Sparkling Waters
 * Frosted Glacier
 * Soda Jungle
 * Rock-Candy Mines
 * Meringue Clouds
 * Peach's Castle
 * Superstar Road

References to other games

 * Super Mario Bros.: Various Luigi sightings are sprites taken from this game.
 * Super Mario All-Stars + Super Mario World: One of the Luigi sightings is a sprite of Luigi from this Super Mario World version.
 * Luigi's Mansion: Dark Moon: The Luigi sighting in Vanishing Ghost House is based on Luigi and King Boo's artwork from this game.
 * New Super Mario Bros. U: The graphics and worlds reappear.

Trivia

 * In the opening scene, Mario's Cap is seen on the table of Peach's Castle.
 * In some of the levels, Luigi's sprite (in his super form) from Super Mario Bros. can be spotted. Other Luigi cameos are from Super Mario All-Stars + Super Mario World and Luigi's Mansion: Dark Moon.
 * Even though Nabbit helps Luigi is multiplayer mode, Nabbit still steals items from the Toad Houses, and the players will have to catch him. It will not work when Nabbit is playing in Co-op mode, and in single-player mode if the player does the trick to play as Nabbit in the level where Nabbit went, the player will still continue playing as Luigi.
 * This is the first game where Luigi makes an appearance, but Mario does not.