Tron

Tron came out, when, in 1980? It was one of the earliest all CG films (almost all, because they interweaved it with live action).

Now, the movie isn't particularly good, even if it has an interesting concept, predating the Matrix-like cyberworld by quite a few years (most people like to point to the bleaker Blade Runner which not only looks a lot better, but has a more interesting story and better acting, as the inspiration for the cyberpunk SF movement, usually attributed to William Gibson's Neuromancer).

What is fascinating is this trailer of its day, which is typical of trailers. If you see the original Star Wars trailer, you get a similar voiceover, and not of a guy saying "In a world...".

As the years have passed, trailers are edited better (if much like every other trailer), and the voiceover has often disappeared in favor of quick cuts.

A new Tron is expected to come out nearly 30 years after the original including Jeff Bridges who is still acting (how old is this guy?).