Most of us have heard of the Unity game engine [unity3d.com], and until a couple of weeks ago we were restricted to using OSX or Microsoft Windows for development: on 26 August, an experimental build [unity3d.com] was released for Linux.
It is still a work in progress and there are a number of issues [unity3d.com], including (the extremely inconvenient) not being able to drag between windows within Unity. I've also had crashes every time I try to add a component through the button, but it works through the drop-down menu.
One less reason to use Microsoft Windows - my partition has been deleted.