Heja together, I wonder how to turn the files I create with Sculptris into nif - format. Is there a way to do so? Since I would love it include them into some game platforms (for private usage of course) which requires nif - meshes.
List a NIF importer/exporter for Blender. Never tested myself, but if it works as it should, all you would have to do is export your sculpture in OBJ format to Blender, then using the NIF exporter script from the link up there, export it into NIF for your game usage.
retopology is something done to create game engine friendly models from a (very) high poly one like what you obtain from a sculpture. Blender does it very nicely. It takes time but Blender really makes it easy.
(very) high poly models are not really something you want in a game, not only because there's a chance the engine will not be able to actually display such model without crashing each seconds, but because it will cripple the framerate.
Retopology is an excellent way to create models that are game engine friendly.
But unlike a retopology you have very few control on how the model will look once it has been reduced to a lower poly version. Sometime it may not really end visually nice when using those automated methods.
I've always exported from 3DsMax or Blender. First, in the case of Oblivion / Morrowind / Fallout / Civilization, collisions, skin, bones and bind to the texture can not be done in Sculptris, and without it the object (static, organics, etc.) will be uncomplete. Secondly, a lot of polygons, yes.
I use Sculptris only for normal map with low-poly models for games.