Yesterday, Bethesda released official footage of the upcoming reboot of Doom. A few hours later, the Doomworld forums published what appears to be leaked footage and cinematics from Doom 4, an earlier version of the same game that didn't meet internal expectations.
In the short clip, a military force on Earth appears to push back the forces of Hell. The original Doom plot, from 1993, involves teleportation experiments on the moons of Mars creating a portal that allows demons into our universe. Before you laugh at the silliness of that story, consider how much the original Half-Life borrows from the outline.
Bethesda will show an updated version of Doom at this year's E3. Judging from that very brief clip, don't be surprise if the game still features humans protecting the earth from skeleton monsters that launch explosive fireballs.