Video game weapons are now in active use by the military in the form of the M-32 MGL. The weapon uses 40mm ammunition that would be a fine addition to Unreal or Quake, let alone Fallujah or Baghdad. In fact, this is the next-generation of the weapon used by Arnold Schwarzenegger and his crew in Predator. Accurate up to 150 meters and capable of putting six shots down range in about three seconds, the six-round M-32 developed my Martin Electronics can deliver far more than just explosive or penetrating rounds—it can also send out non-lethals such as video imaging rounds to reconnoiter the area before troops move in, signal rounds, or illumination rounds to light up areas.
Image courtesy of DefenseReview.com.