Comment 335 for bug 1

> would it be possible to create "openX" or similar,
> essentially as a translation library for DirectX->OpenGL

As per http://en.wikipedia.org/wiki/Comparison_of_Direct3D_and_OpenGL

"Several partially functional ports of the Direct3D API have been made by Wine, a project to port common Windows APIs to Linux, but this work is difficult due to the dependency of DirectX as a whole on many other components of Windows."

IOW, Wine is your best (software libre) option at the moment.

> the only thing keeping Windows on my home system is my addiction to <a game>

Do a search on http://appdb.winehq.org/ to see to what extent people have gotten that game you want to run working. You might also want to consider virtualizing a version of Windows just for gameplay if it turns out that it doesn't run great yet...