iA Writer - Minimal Design, Maximum Focus
Unity - The multiplatform game creation tools for everyone.
MacDown - MacDown is an open source Markdown editor for OS X, released under the MIT License.
Godot Engine - Feature-packed 2D and 3D open source game engine.
MWeb - Pro Markdown writing, note taking and static blog generator
Blender - Blender is the open source, cross platform suite of tools for 3D creation.