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.
Unreal Engine - Unreal Engine 4 is a suite of integrated tools for game developers to design and build games, simulations, and visualizations.
ThumbZilla - Awesome thumb stomping and kicking action game.
Corona SDK - Cross-platform mobile app development.
Warlight - Warzone is a customizable Risk-like strategy game where you compete with your friends to conquer the world.