Loki software is strange, they focus on Linux software, GameSpy agree with me, and caught up with them recently. They made their name with the title Civilizations: Call To Power, which was released over a year ago. Commercially developing Linux games, or ports for Windows games to Linux seems to be a risky business as far as I can tell, to that they answer, "We believe that Linux needs to be successful on the consumer desktop, and that games are a necessary part of that success. From that standpoint, our games contribute to the growth of Linux as a platform".
One of their main problems of course is not that many people install Linux and use it to play games on, "The consumer market is still gearing up for the kind of explosive growth that Linux has experienced in other markets." He follows with, "And once you've got Linux installed on your computer, what then? Well, how about a game!"
Later in the article he answers an interesting question about the theory of a cross platform Direct x, "Microsoft had to push hard just to get Windows developers to use DirectX. It's not clear that developers with alternatives would choose DirectX. Moreover, a cross platform DirectX would always be faster, more stable and have more features on Windows than on any other platform."