One way to start writing Doomworld fan fiction is to pick a specific aspect of the Doomworld that interests you. For example, if you're into the technology in the games, you could write a story about a group of scientists trying to reverse - engineer demon technology. Then, establish your writing style. Are you going for a gritty, action - packed style like the games, or a more introspective, character - driven style? Once you've decided on that, start writing your first draft. Don't worry too much about grammar and spelling at first. Just get your ideas down on paper (or on the screen). Then you can go back and edit it later to make it more polished.
To start writing Doomworld fan fiction, begin with a strong opening scene. It could be a battle scene, a discovery in a dark corner of a hellish realm, or the Doomguy receiving a strange mission. After that, build your plot gradually. Decide if you want a linear plot or one with lots of twists and turns. As you write, don't forget to describe the environments vividly. The Doomworld has some really unique and terrifying landscapes, like the blood - soaked halls of hell or the desolate, demon - infested Earth cities. Make the reader feel like they are there.