We can disable any file type we do not with to support. And we can add our own filetype, a custom one. But, for modding, why not just support some good standard ones that makes it easier to mod?
I do work on multiple items at once so now I can work on the physics and start planning the AI.
As for irrlicht it allows me to support either dx 11 or 9, or Open GL 2, so changing the configuration to allow user selection. This was already coded for DX9 and OpenGL, added DX11 and it works so no deed to rebuild the code to change drivers. And users on older systems can drop to DX9 with notepad to change the driver in config.xml