PICO-8 - Lua-based fantasy console for making and playing tiny, computer games and programs.
Unity - The multiplatform game creation tools for everyone.
Moai - Moai is a spiritual successor to one of the elder gods of pixel editing: Autodesk Animator.
Godot Engine - Feature-packed 2D and 3D open source game engine.
GnuPG - GnuPG is a complete and free implementation of the OpenPGP standard as defined by RFC4880 (also known as PGP).
Blender - Blender is the open source, cross platform suite of tools for 3D creation.