Construct 2 - Scirra Construct is a 2D game development engine with a focus on building games visually.
Kodu Game Lab - Kodu lets kids create games on the PC and XBox via a simple visual programming language.
Godot Engine - Feature-packed 2D and 3D open source game engine.
Unreal Engine - Unreal Engine 4 is a suite of integrated tools for game developers to design and build games, simulations, and visualizations.
BYOND - BYOND is the premier community for making and playing online multiplayer games.
Corona SDK - Cross-platform mobile app development.