Unity - The multiplatform game creation tools for everyone.
TripleA - TripleA is a free (under GPL) turn based strategy game based on Axis & Allies board game.
Godot Engine - Feature-packed 2D and 3D open source game engine.
Puzzle Strike - Puzzle Strike is a Puzzle, Board, Single and Multiplayer video game created and published by Sirlin Games.
Blender - Blender is the open source, cross platform suite of tools for 3D creation.
Lux Delux - Lux Delux is a game of strategy and domination inspired by the board game Risk.