Topogun is described as 'TopoGun is a stand-alone resurfacing, and maps baking application. The resurfacing functions in TopoGun will help you modify and/or recreate the edgeflow of your digital 3D models'. There are more than 10 alternatives to Topogun for a variety of platforms, including Windows, Mac, Linux, Android and iPad. The best alternative is MakeHuman, which is both free and Open Source. Other great apps like Topogun are ZBrush (Paid), Sketchfab (Freemium), Bforartists (Free, Open Source) and VRoid Studio (Free).
MakeHuman is an interactive modelling tool for creating realistic 3D human characters. These models can be exported to several computer graphics and animation platforms including Blender, Unity 3D, Unreal Engine, OpenSim and Second Life.
Sketchfab is the first web service to publish interactive 3D content online in real-time without plugins. Every new format has its global platform: videos have Youtube, photos have flickr, sounds have Soundcloud... Now 3D files have Sketchfab.
pixiv has released "VRoid Studio", a character maker that allows users to create, in easy steps, 3D model characters which can be used in various VR\AR platforms as well as the production 3DCG animation and games.
ZModeler (or Zanoza Modeler) is a 3D modeling application. It is aimed at modelers who model for computer games such as 18 Wheels of Steel, Grand Theft Auto, Need for Speed, Midtown Madness or similar video games.