Unity - The multiplatform game creation tools for everyone.
skribbl - Word guessing based on drawing.
Godot Engine - Feature-packed 2D and 3D open source game engine.
LetsDraw.It - Guess and Draw, Drawing Battle, Pictionary, Copy picture - online drawing games where you can compare your skill with others.
Blender - Blender is the open source, cross platform suite of tools for 3D creation.
gartic.io - Draw, guess, and win!