Microsoft has dropped a few hints in the past about playing games across all of its platforms. Now Engadget is reporting that Microsoft has demoed a game developed in Visual Studio which plays on Windows PCs, the Xbox 360, and a Windows Phone 7 Series prototype device. The game demoed was apparently a simple Indiana Jones platformer by Microsoft’s Eric Rudder at TechEd Middle East.

It seems the game plays on Windows PCs using a keyboard, the Xbox 360 using the gamepad, and the phone device with accelerometer and touch controls, and has 90 percent shared code. The most amazing thing is that you can save the game on any platform and pick up where you left off on any platform. Of course this will be made possible by using Xbox Live.

A true cross-platform innovation this, but it will probably be limited to casual games. It would also mean that video game developers will be able to work on a single project that works with all of Microsoft’s current platforms.