Outcast is a PC game that came out in around 2000. While I haven’t played the game, it gets mentioned often in discussions on Voxel graphics because it used the technique for its terrain rendering. Specifically, there is a presentation the creators gave at GDC in 2000 which is supposed to be floating around the net in the form of a paper. It discussed the techniques used for the game is some detail.
The company however went bust ages ago and the link most papers refer to is dead. Luckily I was able to locate the material the other day on some website, albeit in the form html pages. They only exist on the server file list however, so you’ll have to visit each page individually.
Here is the link to the hosted pages, you will have to click on the html pages in order to read them. If you’re interested, I suggest you save them before they disappear again!
Outcast GDC presentation link: http://eltrollo.el.ohost.de/files/files/eltrollodevu/html/outcast-gdc/