Ken Silverman's Official Home Page
advsys.net
advsys.net
I also think the VOXLAP engine was used in this one indie game called Ace of Spades, at least before it changed hands: https://web.archive.org/web/20161031124717/https://www.rockp... and http://advsys.net/ken/voxlap.htm
I'm mentioning this because that game had a lot of charm (like Sub Rosa also did), but also because it was immensely cool to see large voxel worlds rendered on the crappy laptop I had at the time without it breaking a sweat.