But yeah, Batutta's right. Voxels are largely useless nowadays. I figure Miner Wars only uses it as a good way to do cheaper (?) procedural destruction.
They're not useless at all. They're still used in a few 3D apps and are quite powerful, and they're used all over in medical imaging stuff. Battutta said (someone incorrectly), that they've been discarded - not that they're useless.
You should go and actually look at Miner Wars. It's not just "cheaper", it's a completely different way of rendering 3D objects. Polygons simply
can not do what Voxels do, at least, they can't do it without being EXTREMELY inefficient.
Voxels are the best way of showing non-uniform volumes. Polygons are a bunch of faces drawn between vertex data points - you could define an entire 3D model in a text based table, for instance (you used to be able to open most .OBJ files with Notepad, I'm not sure if you still can - I think there was a text export function way back when).
Now, when it comes to creating a 3D object with vertices and polygons, you have to worry about a lot of things - connecting the polies so that there's no gaps, making sure that what's called the "poly flow" is well laid out and organized, etc - all of this helps to reduce rendering errors when creating polygon-based images. It does, however, require a lot of forethought and planning when creating a model. This means live, fully functional terrain deformation is essentially impossible, as you would have to move around these polygons quite a lot, and you would end up with several errors - for instance, hyper-sharp points, smoothing errors (caused by small radius light sources being applied to very large polygons), flipped faces, etc), when it comes to extreme deformation.
Voxels, however, are arranged much like a 3D grid - if you typed it all out in a text file, it would be in a table with each point's X, Y, and Z coordinates.**
Each of these little "voxels" are essentially representing a single "unit" of space (don't think of them like polygons and vertices, they are a TOTALLY DIFFERENT 3D REPRESENTATIONAL/DATA METHODS). What this means is that a "voxel" object has absolutely no issue with terrain deformation, because if, say, I blow a hole in an asteroid, the game simply creates new "dots" and destroys the old ones - a chunk of the object is simply blown away and new data is made where it used to be.**
** Now, I'm not TOTALLY SURE that this is the 100% PROPER definition. The results, however, speak for themselves - Voxels are able to produce shapes and mesh detail that is difficult, if not impossible, with polygonal based formats.****
****That's not to say voxels don't have drawbacks that polygons don't have - they're two equally well-off 3D representational/data methods, for their own strengths/weaknesses. But that's not the point of this argument.