Steven Lisberger’s 1982 science fiction film Tronbecame a cult classic for its pioneering use of CGI and its focus on the emerging world of video games, but it took 28 years for Disney to produce a sequel. Joseph Kosinski’s Tron: Legacy,which celebrates its 15th anniversary on Dec. 17, again pushed the envelope of digital effects — with mixed results. While its modernized spin on the virtual world of the Grid looks stunning, the de-aging effects used to create a young version of Tron star Jeff Bridges wound up looking deeply disturbing. But nightmarish visuals weren’t the worst thing Kosinski and Tron: Legacy writers Edward Kitsis and Adam Horowitz did to the franchise. They also stripped away the weirdest and coolest part of Tron’s story, leaving behind a plot that was both cliche and nonsensical.