New Super Luigi U has been available to download from the Wii U eShop for a short while and has breathed new life into New Super Mario Bros. U.

Although, technically deemed DLC, it's a much longer experience than the downloadable software added to New Super Mario Bros. 2 and this approach came from the development team wanting to do something a little more meaningful than the 3DS outing.

Nintendo President Satoru Iwata recently sat down with director Masataka Takemoto and executive officer Takashi Tezuka for the latest installment of Iwata Asks, and they revealed how they weren't entirely happy with the DLC releases being added to New Super Mario Bros. 2.

Tezuka confirmed the idea for Coin Rush Mode came from the team developing the 3DS title and they moved forward with that first as it was going to hit the shelves before New Super Mario Bros. U

However, as we were working on it, the sameness of the idea began to bother me, so I started thinking we should come up with a different idea for New Super Mario Bros. U.

The experienced duo were clearly concerned that players would wonder why the extra levels weren't in the game in the first place and accusations of Nintendo holding back content to sell at a later date flew around when they did finally emerge.

Iwata said Nintendo began developing the additional packs for New Super Mario Bros. 2 once the game was out and it had analyzed how people were playing it.

Our intention was to prevent any sense of the original game being slim in content because there was going to be downloadable content, but nonetheless, some did wonder why it wasn't in there from the start.

Interestingly, Tezuka said he still wasn't convinced about the Boost Rush Mode in New Super Mario Bros. U when it launched alongside the Wii U in 2012 so he decided to "consider whether there were any other good approaches".

This is where New Super Luigi U came in. The developer wanted to create an experience tailor-made for advanced gamers to add some extra challenge that may not have been found in Boost Rush Mode.

The pair also revealed how the new addition became centred around Luigi and it turns out during a meeting Iwata mentioned 2013 was the year of Luigi and this inspired Tezuka to shape the content around the green-clad plumber. On top of this, it was decided early on that Mario would not be in this game - after all, this was Luigi's time to shine and there was no way the team wanted his brother to muscle in and steal the limelight.

This presented a problem though, as New Super Mario Bros. U is a multiplayer experience and so Tezuka and Takemoto scrambled to find other characters to help Luigi through. Taekmoto explained how they went about deciding who to adopt:

When we decided on Luigi as the main character, I talked with Tezuka-san about how I was absolutely against having Mario make an appearance. The idea came up of using three Toads, but when three Toads show up, the screen gets confusing, so I hounded Tezuka-san about seizing this chance to use a new character.

I thought the only choice left was Nabbit! In New Super Mario Bros. U, you chase around Nabbit, but I thought it would be fun to keep Nabbit's ability to slip past enemies and use him as a player-character.

All of a sudden New Super Luigi U had an element that wasn't aimed at advanced players as Nabbit became the perfect choice for beginners, what with him being totally indestructible.

Tezuka also explained how Nabbit is not just a multiplayer character and can be summoned in the game's single-player mode by inputing a particular command when entering a level, although he didn't share what players must enter in order to encourage them to discover it for themselves - something quite rare in the age of the internet.

In terms of the level design, it was decided that New Super Luigi U would feature much smaller levels than the original installment. This came about once Takemoto replayed Super Mario Bros. 3 on the NES and realised how the New Super Mario Bros. series had expanded the levels as time had gone on. As he enjoyed the shorter courses he wanted to integrate this element into the new downloadable content. This is where the timer came in, with the team deciding to limit each level to 100 seconds to increase the challenge and shorten the courses.

It turned out to be the kind of game that even people who aren't great at video games will be able to clear if they repeatedly challenge themselves.

Naturally, using the same development team that created New Super Mario Bros. U may have led to the new DLC feeling very similar to Mario's adventure. To combat this Tezuka said he brought in New Super Mario Bros. 2 team members who were kicking their heels in order to freshen up ideas as the home console title was so different to the portable adaptation.

You can see what we thought to the new title in our New Super Luigi U review and as always you can check out the full Iwata Asks interview by clicking the link below.

Have you downloaded New Super Luigi U? Let us know what you think to its approach to DLC in the comment section below.