Every DOOM mod is canon, so they say, and it's justified by Doomguy choosing to stay in Hell at the end of Final Doom or Doom 64 (don't remember which) to keep killing demons to take his revenge on them. Time is all fucky in Hell so for thousands of years he roamed around killing demons before they trapped him, and then we pick up the story on the Samuel Hayden (who is somehow also an angel) timeline where Hell is used as a source of electrical power.
Every DOOM mod is canon, so they say, and it's justified by Doomguy choosing to stay in Hell at the end of Final Doom or Doom 64 (don't remember which) to keep killing demons to take his revenge on them. Time is all fucky in Hell so for thousands of years he roamed around killing demons before they trapped him, and then we pick up the story on the Samuel Hayden (who is somehow also an angel) timeline where Hell is used as a source of electrical power.