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 the main player, 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 addition to and the  controls in New Super Mario Bros. U. This game was also released at retail as a standalone game which does not require New Super Mario Bros. U in order to be playable. It is part of "The Year of Luigi", which celebrates the 30th anniversary of Luigi's debut.

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, but 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 contain only 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

Differences between retail and digital versions

 * The image that appears when the game is loading is changed from the one in New Super Mario Bros. U.
 * Every message box is now green, including those that appear before the title screen.
 * The title screen has been changed significantly, the New Super Mario Bros. U + New Super Luigi U logos have been replaced by just the New Super Luigi U logo alone, the ground tiles have been changed, and Mario is no longer present.
 * The button to go back to New Super Mario Bros. U on the file select screen has been removed.

References to other games

 * Super Mario Bros.: Various Luigi sightings are sprites taken from this game.
 * Super Mario 64 DS: The portrait used to enter Big Boo Battle is reused as a hidden Luigi.
 * Super Mario World: Super Mario Advance 2: 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: As New Super Luigi U is an expansion pack of this game, most of the elements from this game 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 World: Super Mario Advance 2 and Luigi's Mansion: Dark Moon.
 * Even though Nabbit helps Luigi in 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.
 * US and Canada Club Nintendo members who purchase New Super Luigi U from the Nintendo eShop by August 1, 2013 and complete the surveys within four weeks after downloading can receive double the amount of coins (for a total of 40 coins) compared to the original amount (20 coins). They also have a chance to win 1 of 980 Luigi pins.