Claystation saidSounds like a bunch of bullshit to me. Maybe he was talking about his glory days on some videogame.
As a marine, I was given instructions by my commander to find a scientist from Delta Labs who had gone missing. I eventually found the scientist in a nearby decommissioned communications facility, where he was frantically trying to send a warning to the UAC on Earth about a colleague's teleportation experiments. However, as he tried to explain the situation to me, another teleportation test takes place and loses containment, at which point the entire Mars base is swept with an incredible shockwave, transforming most of the base's personnel into zombies as the forces of Hell invade through the teleporter's portal.
Now forced to fend off attacks from zombified base personnel and the demons from Hell, I return to Mars City, where I'm remotely given orders to link up with another squad of marines (Bravo Team) and get a transmission card containing a distress call to the main communications facility to call for reinforcements. Our marine squad was ambushed by demons and slaughtered in the EnPro Plant, and although I recovered the transmission card, I was too late to prevent the bulk of equipment at the communications facility being destroyed. Upon arriving at Delta Labs, I learn of the details of an archaeological dig under the surface of Mars. The dig was excavating the ruins of an ancient civilization discovered on Mars, and had produced a relic known as the Soul Cube. According to a scientist I found alive in the labs, the Soul Cube is a weapon created by the ancient civilization to defend against the forces of Hell.
Upon my discovery of the portal, I was taken directly into Hell, where I proceeded to fight my way through the large number of demons to the Soul Cube, defeating its demonic guardian. I was then able to reinitialize the teleportation equipment left by research expeditions into Hell and return to the Delta Labs. It was here I found the BFG 9000. It was with this weapon I was able to defeat the Cyberdemon in combat. This is the first time I have been able to open up about these killings.