Doom 2016 had a pretty substantial single-player campaign—a good thing, because what made it so amazing definitely was not the multiplayer options when it launched. Doom Eternal's campaign is going to be beefier still, according to id executive producer Marty Stratton.
"It's definitely bigger than Doom 2016, longer," Stratton said. "I think the way we're challenging players will probably make it play a bit longer. My guess right now is it's in the 18-22 hour range on a pretty complete playthrough."
Stratton points out that people approach games differently, and so the range of playthrough times for 2016's Doom reboot was pretty wide: some players shot through it in 14 hours, while others spent more than 30 hours scouring every gory nook and cranny for the collectibles and secrets strewn throughout the game on their first run.
There's still time for Doom Eternal's campaign to change, but Stratton seems pretty definite about the idea that this is going to be a somewhat longer ride. And hey, that sounds great to me—after all, at least part of it will be on a grappling hook that only attaches to meat.