This paper produces a good result: http://large.stanford.edu/courses/2007/ph210/otey2/. If you game is OK sounding synthetic, I've had good results simulating a string plucked off center, decay each harmonic proportional to the frequency, then adding reverb.

A sound font or VST plug-in with appropriate licenses may be another route, but I can't speak to how difficult that would be to work with. It's on my to-do list.