Back in 1982, Disney's ground-breaking hi-tech SF movie Tron opened in the same week as the epoch-making decision at Pittsburgh's Carnegie Mellon University to order its students to abandon pen and paper and work entirely on computers. In that film the 43-year-old Jeff Bridges played Kevin Flynn, a brilliant designer of computer games. Crossing a vital boundary, he actually entered a video game, moving from being a "user" to becoming a "programme", his aim being to frustrate an arch rival. Now, 28 years and several quantum leaps in technology later, there is a sequel, Tron: Legacy – not quite a record as Return to Oz came 46 years after The Wizard of Oz.

It's 2010, the 61-year-old Jeff Bridges is again Flynn. He's been missing for over 20 years, during which time his son Sam (Garrett Hedlund) has grown up inheriting his father's gifts and multibillion-dollar business. It transpires that the grizzled Flynn had gone back into the video game and there created a doppelganger, the menacingly fanatical perfectionist Clu (played by a CGI version of the young Bridges). So the intrepid Sam, like his father before him, enters the game, though remaining a "user", charging into the Silicon Valley to root out evil and save Dad.

Set in a murky, near-monochrome world throbbing to the music of the French duo Daft Punk, the film is a political allegory about totalitarianism with talk of genocide. A sub-plot involves a dithering Blair-like figure (an epicene dandy inevitably played by Michael Sheen) who yammers on about his crucial importance to the alliance before being blown away. Four years in production and costing $200m, the movie is indubitably on the cutting edge technically. But dramatically it's a solemn mishmash of The Wizard of Oz, 2001, Star Wars and Blade Runner.c