Well, considering that this thread is the first time I've heard the game mentioned, I'm not really sure how many Linux gamers even know that it exists. It needs to be submitted to linuxgames.com and happypenguin.org so that Linux gamers can find it. I don't know how much that will help sales, but there is a decently sized crowd who will gleefully pay for Linux games (assuming that they have the money at that paricular time anyway).
Most everyone that writes commercial games for Linux has a nice long rant in them about the subject though. The problem is figuring out how best to deal with the Linux users who use Linux simply because of the all of the free software, the Linux users who happily pay but aren't gamers, and the Linux gamers who will happily pay for a good game (a much
smaller crowd). And you also have Wine to deal with, since some people will always just buy the Windows version and play it through Wine. Usually that happens because the Linux version becomes available months later, and/or cost more than the Windows version at the time they buy (Windows versions depreciate faster so their prices drop far more rapidly than the price of a Linux or OS X title do). Of course, no one has been able to figure out how to handle all of that yet. One thing that I did see recently, and thought was interesting, was a Linux port that required 200 pre-orders before that would finish/release it, primarily because their previous Linux port didn't sell nearly well enough. I'm pretty sure that they got those orders within about a week too.
And if you need to free Linux support code wise then you know you can always turn to me.
I'll try and help out with Linux and OS X ports without the need for monetary compensation, at least until it's more realistic to do it all in-house. I don't make money as a coder (not my job), so, as long as time allows it, I'll work on anything for next to nothing (a free copy of the game in question is plenty