Bethesda has a new blog post about Doom's single player campaign and how its various mechanics work in harmony. To me it sounds almost like a dance; constant movement, weapon management, spatial awareness and a persistent rhythm of killing demons. The piece is a bit too positive and gushy--this is coming from the game's publisher, after all--but it has some decent info. I particularly like how Executive Producer Marty Stratton describes the player progression and upgrade system: “We want you to feel like a badass no matter how you play.”
This means you're never permanently stuck with upgrades or choices you make, and you can swap out perks to tailor your space marine to a given situation. I really like this flexibility because I don't want to be "Rocket launcher Bruce Lee on a skateboard" through the entire campaign.
I like these expository articles but I feel like they're all starting to say the same general things over and over. I really want id to do a nice long stream of Doom sometime soon so we can see how the gameplay works organically, before the game's launch on May 13th.