You can "convert" applications/games to run on Linux, it just requires highly-professional skills, as most of popular games are common in the Linux world (Q3,UT ..).
But why to convert things, while there is much more open source sw. Again the problem is (as stupid as it sounds) that the whole thing is based on a great spirit of non-profit knowledge sharing. So you cannot make ppl to write free software the way you want, enjoy what you've got... or write it yourself


Cheers
Chef