From the guy's site:

In late 1998, I was commissioned to compile and produce the soundtrack for a
sequel to the film "Tron". A draft of the story had already been written and
early filming had begun (as reported by ZDNet on July 27, 1999). As I
understand it, the film was kept in great confidence with the producers as
Pixar was still in negotiations with Disney about the responsibilities of the
production teams.

"Rise Of The Virals" was a fantastic, but much darker storyline from the
original -- different from the "Into The Machine" pitch made to Disney by
another party. It involved updating the ENCOM universe to a networked system
(thanks to the Internet), but also created a darker world -- full of programs
abandoned as buggy systems (or "mutants") and abused by corrupt users as viral
systems. Furthermore, the story included the death of Flynn and presented
questions about the digital life of programs lasting beyond the mortality of
their creators -- the users.

My task was to compile great underground artists to create a new soundtrack for
this darker world of Tron. After the completion of the initial tracklist and
first production draft of the soundtrack, it seemed as if negotiations between
Pixar and Disney had broken down. Funding for the project was eventually pulled.

I have been most excited to see the announcement of the third film, the new
"TR2N" (Tron: Legacy), especially with the involvement of those who will be
creating the new soundtrack. It is obvious to me that "Tron: Legacy" takes
place after "The Rise Of The Virals" without abandoning its first concept.
Perhaps that is why we've seen sites like Flynn Lives creep up in anticipation
of the new film.

I've decided to release the preliminary version of the soundtrack which
includes a special remix of Journey's "Any Way You Want It" produced
specifically for "Rise Of The Virals". Journey provided two songs to the
original "Tron", and their song "Separate Ways" will reportedly be on the
"Legacy" soundtrack as well. In any case, since the story of "Rise Of The
Virals" takes place between the first "Tron" film and the upcoming "Tron 2:
Legacy", I can't think of a better title for this material other than "Tron
1.5". I hope you enjoy the music these artists have put such great work into.

The soundtrack can be downloaded here.