When hacker Kevin Flynn (Jeff Bridges) first got zapped inside a computer grid in 'Tron,' the digitized ether was a much simpler place. Black, minimalist, streaked with neon piping and floaty geometric figures, it was home to enslaved 'programs' who played deadly gladiatorial games (Frisbee, Jai-alai) at the whim of an evil operating system with a giant Lego head. Everyone wore dorky uniforms. There was no downtown, no crowded arenas, no nightlife and certainly no drunken hobos. My, how times have changed. In 'Tron: Legacy,' the long-awaited sequel to the innovative 1982 Disney film, Kevin's son enters the Grid in search of his long-lost dad. It's still a monochromatic world streaked with light: bluish for good guys, reddish for bad. But the programs are - what's the phrase? - party animals. They hang out at dance clubs. They drink cocktails with cute glass umbrellas. Head-bobbing DJs spin Daft Punk. A bleached Michael Sheen swivels his hips, swirls a cane and channels Malcolm McDowell. And when a program hits bottom, he huddles with a bottle on the sidewalk. Ummm ... what? Let's return to the so-called real world, for a moment. Cocky young Sam (Garrett Hedlund, all eyebrows and swagger) hasn't seen his pa since 1989, when Flynn Pere disappeared off the planet after talk of 'a miracle' in the Grid. When old friend Alan (Bruce Boxleitner, also reprising his role as the program Tron) reports a page from Kevin's old phone at the video arcade, Sam checks it out. There he gets sucked into the Grid, where he meets his father's power-hungry alter-ego - Clu, played by a young, performance-captured simulacrum of Jeff Bridges - and gets conscripted into the games. After a few rounds of mortal Frisbee and lickety-split 'light-cycle' races, Sam hooks up with Quorra (Olivia Wilde), a genial program who brings him to the actual older Kevin in his well-appointed batcave. Kevin, now bearded, barefoot and totally Zen, tells the story of his entrapment over an elegant dinner with roast suckling pig. Ummm ... huh? Just to be clear: the original 'Tron' was groundbreaking, goofy and inscrutable, with eye-popping graphics and lots of wooden dialogue. This sequel is also goofy, also eye-popping - see it in IMAX 3D if you really want to fry your optic nerve - and also weakly scripted, borrowing from various 'Star Wars' films plus 'The Elephant Man' ('I'm not a program!'). And yet the sheer size of the thing works against it: the effects are absolutely spectacular, but they blow the goofy-cheesy quotient straight through the roof. In revisiting the Grid, first-time director Joseph Kosinski and screenwriters Adam Horowitz and Edward Kitsis have hyperbolized every last detail. So, yes. Roast pig in three dimensions. Regarding Jeff Bridges' digital de-aging: it's creepy. It's a little less creepy on Clu's face (he's not human, anyway) than on Kevin's in a scene from 1989, but on either of them it has the waxen look of storefront mannequins - or over-Botoxed socialites. Those weren't around in '82, either. TRON: LEGACY Rated: PG for sequences of sci-fi action violence and brief mild language. Running time: 127 minutes. 2 and a half stars (out of four) amy.biancolli@chron.com XXX - End of Story3D 