Warner Bros. Entertainment and MGM have partnered to invest in Kabam, the companies said Tuesday, tightening links between the producers of the upcoming “Hobbit” film and the maker of a popular game based on it.Warner Bros. Home Entertainment prexy Kevin Tsujihara and MGM CEO Gary Barber will join the board of the San Francisco-based group founded in 2006. “We look forward to added insights from Mr. Tsujihara and Mr. Barber, two media company executives at the top of their game,” said Kabam founder and CEO Kevin Chou. “Partnering with Warner Bros. and MGM is a natural fit for Kabam as we create new storylines and extensions of Hollywood studios’ intellectual properties for millions of gamers worldwide.” The transaction follows the recent release of “The Hobbit, Kingdoms of Middle-earth,” a game co-developed by Kabam and Warner Bros. Interactive Entertainment and based on Peter Jackson’s “The Hobbit Trilogy” from New Line and MGM. First pic hits theaters Dec. 14. Kabam and Warner are co-developing another “Hobbit” game to play on Web browsers, “The Hobbit: Armies of the Third Age,” for release early next year. “We partnered with Kabam almost a year ago to deliver incredible games for “The Hobbit” trilogy, arguably one of the top intellectual properties in the world,” Tsujihara said. “As we worked with Kabam, it became clear that a closer, more strategic partnership made sense for us both. Kabam is a leader in the industry, and we look forward to being a part of their continued growth.” Other Kabam titles include “The Godfather: Five Families,” “Dragons of Atlantis,” “Edgeworld” and “Kingdoms of Camelot.” Financial details weren’t released. Kabam’s investors also include Google, Intel and venture capital firms Canaan Partners and Redpoint Ventures.