There is a modification for an existing game (Unreal Tournament) that is going by the name TacOps/Tactical Ops. This modification is a woefully inaccurate portrayal of real tactical operations, with unrealistic weapons and combat "simulation".
You can find the modification at http://www.planetunreal.com/tacticalops/
I just wanted you guys to know as it may violate some copyright laws, or something as such. With the behaviour of the team and their fans at that site, it may very well give TacOps a bad name.