Roomtodo - Simple yet powerful online tool for interior design and floorplans with built in walkthrough module.
Unity - The multiplatform game creation tools for everyone.
Sweet Home 3D - Sweet Home 3D is a free interior design application that helps to draw the plan of house, arrange furniture on it and visit the results in 3D.
Godot Engine - Feature-packed 2D and 3D open source game engine.
Palette CAD - Palette CAD is one of the easiest 3D design software for those people who want to use a simple to use program for interior designs.
Blender - Blender is the open source, cross platform suite of tools for 3D creation.