Unity - The multiplatform game creation tools for everyone.
Wikids - An encyclopedia that talks to your kids
Godot Engine - Feature-packed 2D and 3D open source game engine.
Litnerd - The Pixar for education, reading program for K-5 schools
Blender - Blender is the open source, cross platform suite of tools for 3D creation.
Pili Pop - Great language learning method for kids