What are some alternatives?
When comparing PlayN and Sculptris, you can also consider the following products
Unity - The multiplatform game creation tools for everyone.
Blender - Blender is the open source, cross platform suite of tools for 3D creation.
Pygame - Pygame is a set of Python modules designed for writing games.
ZBrush - ZBrush is a digital sculpting and painting software solution.
Castle Game Engine - An open-source 3D/2D game engine for ObjectPascal.
Cinema 4D - Cinema 4D is a 3D modeling, animation, motion graphics and rendering application.