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The closest you will get to this I think is Unity although that doesn't currently have Linux support.

All programming is done using Mono and it also contains a load of proprietary tools for asset generation as well as stuff for AI etc.

Unity 3.5 now has flash export, so I think even Linux is now supported?

Yeah... But even with Mono you have to use the proper classes for display, so it's not completely code once play anywhere.

It's Mono running on top of Unity's own graphics/control/audio abstraction