[jiggy2011]

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.

[robert00700]

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

[Pedrom]

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

[robert00700]

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