Cd-i (Compact disk interactive)
This now obsolete system was the first fully interactive digital disk system, with capabilities which still, in some areas, surpass DVD or Blue ray systems.
Devised by Philips, it was perhaps too early on the market place and arrived before the public really understood the concept of 'interactivity'.
David Matthewson was a long term consultant to Philips and worked on many of the early CD-i programmes, as well as authoring tools and design concepts and systems.