Don't know about that one. There have been several Vietnam based FPS games starting with one using the old Duke Nukem sprite based DOS engine to one with ultra realistic graphics complete with deformable terrain.
Some, like Battlefield Vietnam, are non linear and allow you to play either side as you command a squad. There are numerous mods available. Others are quite linear and way too unrealistic in their game play even though the graphics are getting extremely realistic.
Do the web search, view the videos, and read the reviews before buying one.
Still, nothing beats the keyboard mouse combo for speed and accuracy compared to a game controller. (Although that may change with use of the interactive systems such as Wii, X Box Kinetic, or similar interactive system on the PS3.)
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