CONV. - Convert YouTube video to MP3, GIF or MP4
Unity - The multiplatform game creation tools for everyone.
Downie - Video download for OS X. Downie supports at this moment over 1,000 different sites.
Godot Engine - Feature-packed 2D and 3D open source game engine.
Yout - YouTube to Mp3 Converter
Blender - Blender is the open source, cross platform suite of tools for 3D creation.