* Wii U comes with custom "Super Mario" title
* Video content beefed up
* System can work with two GamePad controllers (Adds industry expert's comments)
By Liana B. Baker and Malathi Nayak
LOS ANGELES, June 5 (Reuters) - Nintendo Co Ltd will launch a console with a dedicated "Super Mario" game title for the first time in 16 years, as the struggling Japanese company hopes the new Wii U will score the rave reviews that helped make its predecessor the world's biggest gaming hit.
Nintendo, which was knocked off its perch at the pinnacle of gaming industry hardware by Microsoft Corp's Xbox in recent years, formally unveiled a white console on Tuesday, saying it will support two "GamePad" controllers designed to look and function like tablets.
The Wii U - which will carry video content from Netflix Inc , Amazon.com Inc, Google Inc's YouTube and Hulu - will hit store shelves in time for the holidays. Nintendo did not put a price tag on the device.
The first console from Nintendo in six years will come with a social gaming network dubbed "Miiverse". But it will need a vast library of software - including the star of its stable, Super Mario - to have any hope of matching the Wii's success.
Nintendo needs to fend off upstart challengers like casual game makers and apps for mobile devices like Apple Inc's iPad, which are making inroads into the $78 billion videogame market.
The decades-old "Super Mario" franchise features its namesake plumber traversing different adventure scenarios. It spearheaded Tuesday's presentation of a plethora of games intended for the Wii U, including "Nintendo Land".
"Every time a new Nintendo home console is announced, we start hearing familiar feedback from long term fans: 'Sounds great but you've got to have a Mario game,'" Nintendo of America President Reggie Fils-Aime told a packed theater at the E3 gaming conference in Los Angeles.
The Japanese gaming company, however, left many in the audience wanting more information - especially on the cost, given that Nintendo is playing catch-up with Microsoft and Sony Corp's heavily discounted hardware.
"I am still not convinced about whether they can retain the audience who bought the Wii, as well as hardcore gamers," said James Brightman, U.S. editor for trade publication Games Industry International.
The new Mario installment will create buzz with gamers but Nintendo could have done more to showcase its hit franchises, such as the noticeably absent "Zelda" title, he added. "There are big questions here, like 'How much is it?' and 'When exactly will it launch next fall?'"
Plus, while Nintendo said the Wii U will have Netflix and Hulu Plus on it, it did explain how it will work or what it would look like on the new consoles, Brightman said.
Analysts said Nintendo, which traces its origins back more than a century to the streets of Kyoto, badly needs a hit.
In 2011, it launched the 3DS handheld device to disappointing sales in part because it initially lacked new versions of its top games.
The original Wii revolutionized the industry by introducing motion-controlled gaming, and outsold rivals like the Microsoft Xbox and Sony PlayStation 3. But sales have been slowing, triggering the company's first annual operating loss and a major stock slide.
While investor reaction has so far been lukewarm on the Wii U, the videogame industry is embracing the first console to hit the market in years. Ubisoft said this week it is developing eight games for the Wii U's launch.
Executives at Ubisoft said the company was lured by the chance to have players use two screens in one game.
"The Wii U is really interesting in terms of asymmetrical game play, with one player doing something and one other player doing something at the same time," Xavier Poix, studio director of Ubisoft France, said in an interview.
But after seeing Nintendo's presentation on Tuesday, M2 Research analyst Billy Pidgeon said Nintendo will need to work hard to explain why a second screen is necessary.
"It is kind of a complicated sell. You're asking people to play games in different ways," he said.
The last time Nintendo published a new Super Mario title when a home console was introduced was in 1996, with the Nintendo 64.
The tablet controller will also have a headphone jack, a camera in the front allowing for video chat, and a microphone and motion gaming capabilities and trigger buttons on the back of the tablet for shooter games.
But Nintendo focused less on the hardware on Tuesday and more on the games it will bring to the Wii U. The company did not give a release date for the latest Mario game but executives showed off different levels featuring its signature fixtures: Mario, Luigi, Yoshi and gumbas.
The company also showed off games made by other companies built for the Wii U, such as Warner Brother's Batman Arkham City: Armored Edition. (Writing, editing by Edwin Chan, Bernard Orr and Richard Chang)