What about "Pariah" ?
This game old of 2 years was made using the UT2004 engine. This could be relatively easy to port.
However, Pariah hasn't been the game of the year and has been rapidely forgotten. I took me at least 2 two and some googling to remember the name of that damn game.
There was a petition for porting Pariah to linux, but there was no answer from the editor of Pariah.
Probably better to forget, but it's at least worth a post...