About the voxel stuff... Voxels are just a way to store volumetric data which can be completely deformable environments, characters and whatever as well as medical scans of for example a human brain. That is it, nothing more nor less. Now there are differnet ways to display voxel data, the oldest one would probably be some scan line raytracing, which works well with software based renderers and exist since the beginning of 3d computer graphics. Something like that was also quite popular for landscapes in computer games between maybe 1995 and 2002 or something like that. As such a technique gets really expensive and memory hungry at a high quality for a high resolution, polygon based rendering, which just needs information about objects surfaces turned out to do the better job, especially with graphics hardware optimized for it. Then for some years voxels seemed to be forgotten in computer graphics until Crytec came up with a voxel based aproach to edit their terrains, which allows the user to actually work with the much more user friendly voxel data, whichs surface is then converted into polygon data using some algorythm like marching cubes and rendered using the todays extremely optimized rendering pipeline for polygons.
Most probably the 3D worms games used some kind of voxels to internally store the worlds, one could probably also talk about voxels in the context of minecraft and the really nice game from dust does also use voxels to define the environments. All these games then use a polygon based aproach to display them, as that is the easiest and most effective to feed todays hardware with.
What I want to say with this is, that voxels are no new magic or whatever like what some people still consider shaders to be, but just some streight forward way to store volumetric data, which can be usefull in many cases, like if you for example have an area with lava, an area of rocks above it, some rocks on top of that and then maybe water as the last layer. If you now want the player to be able to dig his way through all these layers, you need this information about the volume, which doesn´t really work with just some polygon surface.
