First Person Shooter video games, more commonly called FPSs, have always been considered violent medium, but back when they were first being made the people being shot started out being quite cartoonish and unrealistic like in Wolfenstein. However from 3-D rendering in Quake to the rag doll effects and blood splatter from the aliens of the Halo universe, the video game industry has been advancing the realism of their FPSs. Ultimately leading to situations where something that is meant to be a game can be taken far more seriously.
http://www.addictedgamer.net/blog/2009/05/29/coming-up-wolfenstein-3d-on-xbla-psn/
One of the original FPS, your mission was to kill Nazis and evil cyborg clones of Hitler. Was banned in Germany because of the Nazi symbolism.
http://wiki.quakeworld.nu/Image:Quake_1_screenshot_320x200_e1m3.png
Several years later, striving for realism quake added a 3-D engine to a FPS.
http://www.gamefaqs.com/xbox/472132-halo-combat-evolved/images/screen-3
Halo Combat Evolved popularized the FPS on X-BOX and making FPSs one of the most played video game types.
http://www.gamergirltay.com/2012/08/realism-in-call-of-duty/
Call of Duty Modern Warfare has the player kill many innocent civilians in the mission, No Russian. There is accurate blood splatter and rag doll effects as the people fall lifelessly after being shot.