Free! THINKING WORLDS is a drag-and-drop 3D scene builder and visual programming editor that allows non-coders to build immersive gaming experiences and simulations. It appears more suited for creating virtual training exercises in large organizations, but with a free developer license it should provide a sufficient challenge for the ultra-techie educator. Beware. This is more of a summer project than weekend quick pick -- just imagine the learning curve if there were Scratch controls for every movement in Sim City. But if you're up to the task, there's still time to join this recently started MOOC on gameification. After all, a tool is only as good as the outcomes it makes possible.
Xcode is Apple's powerful integrated development environment for creating great apps for Mac, iPhone, and iPad. Xcode includes the Instruments analysis tool, iOS Simulator, and the latest Mac OS X and iOS SDKs.
"The Teacher Roadmap provides instructions for teaching the "Game Development with XNA: Semester 1" material. This is an exciting CS course that allows students to apply their basic foundation in programming to game and simulation development using C# and the XNA framework. The complete curriculum is available below."