One of the developers (Wolfire's David) is building his game using the Unity game engine, which exports to Linux but only runs on OS X and Windows. Other engine

One of the developers (Wolfire's David) is building his game using the Unity game engine, which exports to Linux but only runs on OS X and Windows. Other engines / development environments like Unreal and Flash are similarly unavailable on Linux. The same is true of most 3D modelling and image editing packages. The tools simply aren't available to make Linux an attractive game development environment.