The opening of 2016's Doom isn't exactly slow compared to your average game, but next to the first ten minutes of Doom Eternal it looks positively restrained. In the former, you start out with a pistol and no armor, while in the latter... well, that's spoiler territory.
IGN has footage of Doom Eternal's opening minutes, running on PC at 4K and 60 frames per second, and you should consider this your final warning if you don't want to know how the game starts. While there's only one major story beat that plays out in the video, it also raises a bunch of new questions. For a less spoilery description of the game's first few hours, you can check out Caty's recent preview.
Alright, so here's how Doom Eternal opens: rather than pick up where 2016's Doom left off, we've both skipped ahead to the demonic invasion of Earth and right past a number of hanging plot points. The last game ended with UAC Chairman Samuel Hayden exiling the Doom Slayer to some unknown destination, but at the start of Doom Eternal, our handsome lad is back and in command of a giant castle floating in Earth's orbit. It also seems that the Doom Slayer's already found a way to bring Vega, the helpful UAC AI, back online after it sacrificed itself in order to open one last portal to Hell.
The Doom Slayer, shotgun already in-hand, takes a portal from his castle to Earth, right near the location of one of the three Hell Priests behind the invasion (and not far from a kaiju-sized demon that lumbers into view). The chainsaw and the game's first hidden collectible are just around the bend. It takes about five and a half minutes for the Doom Slayer to get through the first major encounter and kill the first Hell Priest, and only a little while more to fully upgrade the shotgun with sticky bombs and a full-auto trigger.
From there it's right into the Doom Slayer's first brush with an Arachnotron, which looks like it'll have a major hand in teaching players how to jump and shoot to the rhythms of their chosen difficulty level. While id Software is promising to deliver a long campaign that'll test players with lots of new demons, it looks like a lot's been squeezed into those opening moments. As for everything that's transpired since the first game, it looks like Doom Eternal's saving answers to those questions for later on.
Doom Eternal is coming on March 20, 2020 for the PC, PS4, and Xbox One—a release for Stadia is also planned, and it'll come to the Switch "a bit later."