Game Center - Game Center brings social gaming to OS X and iOS apps.
Unity - The multiplatform game creation tools for everyone.
OpenGameArt.org - A site dedicated to sharing artwork & other assets for game development.
Corona SDK - Cross-platform mobile app development.
SurvivalCraft - SurvivalCraft is a mobile action and adventure game that is based on the wildly popular Minecraft platform.
Unreal Engine - Unreal Engine 4 is a suite of integrated tools for game developers to design and build games, simulations, and visualizations.