Quote Originally Posted by Caraway View Post
That said, you can definitely release a work entirely closed source on Linux (there are a number of these alread) and OpenGL allows you to do that as well so there'd be no reason that if this game were to be ported to OpenGL (it is a DirectX game, despite the poster above saying they didn't notice any runtimes installed) that it couldn't be moved to a Linux platform with a bit of work.
That was a random guess, on little research. Doing a bit of Googling it seems it's DirectX 9c.