In 1994 the German government placed restrictions on ID Software's DOOM which expired as of 31 August 2011. The restrictions, or “Indexing”, put the game on the same level as pornography. Anyone under 18 could not buy or play the game and it was not available or advertised anywhere which might expose its “sadistic bloody violence” to minors.
Doom and Controversy: A History of Violence
When ID Software's seminal first-person-shooter DOOM was released in 1993 it both defined the FPS (First-person shooter) genre and changed gaming forever. The ultra-violent heir-apparent to ID's 1992 effort Wolfenstein, where players stalked a German Castle killing Nazi's, drew criticism in the States for its pixelated depictions of gore and quasi-Satanic imagery. While conservative watchdog groups with epic names like Killology Research Group, founded by Dave Grossman, suggested the game may prime youth for mass murder, the game was still available unrestricted (this was before, and partially the cause for, the ESRB self ratings system). In Germany the game's violent imagery put it on the “no-no” list, which means DOOM fared better than Wolf3D which was banned outright due to its Nazi imagery (Germany is one of the only 1st world countries which bans any and all NAZI imagery, including the sale of Mein-Kampf which is available on bookshelves across America).
DOOM implicated in American School Shootings
While initially shocked by the game which spawned the Computer FPS genre by including multi-player Online gaming and custom level editing options, Americans eventually embraced DOOM and by 1999 the blotchy pixel-gore was almost laughable compared to the true 3D limb hacking which had developed in the six-year interim. But In the aftermath of the Columbine High School shooting, DOOM was again the center of seriously bad publicity. Rumors circulated that Columbine gunmen Eric Harris and Dylan Klebold had created custom DOOM levels, called WAD files that were based on the halls of Columbine High School. Eric and Dylan were avid Doom players, two of the nearly 10 Million users who had installed the game Demo.
Super Columbine Massacre RPG - Doom, Columbine and Controversy

Modern Game Violence
DOOM and Columbine made headlines again with the release of Super Columbine Massacre RPG in 2007.
Super Columbine Massacre RPG is an educational Role Playing Game where users take up the roles of Eric and Dylan in a fairly accurate retelling of the events of April 20th 1999. After the gunmen commit suicide, users play a special “Hell” level where Eric and Dylan are outmatched by the hellish monsters from DOOM.
Doom ban lifted in Germany
Members of Germany's Bundesprufstelle panel, or Federal Department for Media Harmful to Young Persons (Yes, this is real), wanted to renew the restrictions on both Doom and Doom II – Hell On Earth this year but nonetheless the restrictions were lifted. Whereas this time last year DOOM and DOOM II were only available to persons 18 and older, now Germans 16 and older may buy and play the game.
What you should be asking
Is the violence in Doom, as Bethesda software argued to the Bundesprufstelle panel, no longer impactful or potentially damaging to youth due to the crude graphics compared to today's ultra-realistic gaming?