3d Game World Design

Every game, whether 2D or 3D require some kind of world editor. Worlds normally consist of exterior terrain populated with entities (trees, houses, monsters, etc.), water, sky and light sources. Very broadly speaking, there are two problems in creating worlds: creating the terrain, and populating the terrain with all those other things (entities, water, sky, light sources.) World design tools help to solve these problems. Some tools deal exclusively with terrain generation, while others help with laying out the scene.

3ds Max - Windows only; commercial. Among survey respondents, 3ds Max was the unanimous choice of commercial tool for object modeling with games.

Blender - Windows, Mac, *nix; free under GPL. Blender is an open source modeling tool, with many advanced features and a very active and dedicated community. The GUI need getting used to, but lends itself to a very efficient work style once learned. A scene exporter and other tools are available for designing in blender.

Maya - Windows, Mac, *nix; commercial.