Games are a niche where that other OS seems to hold sway. There is news that idSoftware will open the sourcecode of Doom 3. Depending on the licence, this could result in cloning to GNU/Linux. That would be fun for some.
see some specs
The graphics depends on DirectX and works with particular graphics cards only. Open the source could allow more diversity. “Carmack intimated that he had the blessing of id Software’s parent company ZeniMax and called on other developers to to follow suit, saying that releasing source code could be of benefit to the entire industry as it allowed new developers to learn their chops.”
I imagine the energy of developers who love FLOSS and gaming could be very useful in the gaming industry. It will be interesting to see whether or not a FLOSS community of sorts can develop from this move. Doom was released under the GPL in 1999. see more FLOSS games.