Okular - Okular is a universal document viewer based developed by KDE.
Unity - The multiplatform game creation tools for everyone.
Sumatra PDF - Sumatra PDF is a slim PDF/DjVu/EPUB/XPS/CHM/CBR/CBZ/MOBI viewer for Windows.
Godot Engine - Feature-packed 2D and 3D open source game engine.
Foxit Reader - Foxit Reader is a free and light-weight multi-platform PDF document viewer.
Blender - Blender is the open source, cross platform suite of tools for 3D creation.