CraftStudio - CraftStudio lets you craft games from scratch in real-time over the Internet.
GDevelop - GDevelop is an open-source game making software designed to be used by everyone.
Unity - The multiplatform game creation tools for everyone.
Project Anarchy - Project Anarchy is a complete end to end game engine and state-of-the-art toolset for mobile.
Wicked Engine - C++ game engine focusing on modern rendering techniques.
Adventure Game Studio - Adventure Game Studio provides the tools to make your own adventure, for free!