Pmx Editor - PMX Editor is for editing 3D model data to be used in MikuMiku Dance.
Unity - The multiplatform game creation tools for everyone.
3DTin - 3DTin is a browser based 3D modelling tool.
Godot Engine - Feature-packed 2D and 3D open source game engine.
DeleD CE - DeleD is a 3D modeler and level-editor combined into one.
Blender - Blender is the open source, cross platform suite of tools for 3D creation.