We got a good eyeful of Doom's single-player campaign yesterday, courtesy of id Software's Marty Stratton and Hugo Martin, who streamed some quality solo demon-killing action on Twitch. But IGN gets credit for revealing the big secret of the day, which is actually really cool—and which, for the purposes of spoiler protection, you'll have to look down to discover.
It's Doom in Doom! Original Doom, retro-Doom, Doom Classic, whatever you want to call it: There are “stubs” of maps from Doom and Doom 2 stashed throughout the upcoming reboot. They're not full levels, but the layouts and textures will be identical to those in the original games, and finding them will unlock the full version the map, which will be accessible from the main menu.
Machine Games did something similar in Wolfenstein: The New Order, but not nearly as extensively: TNO only included the first level of the original Wolfenstein 3D, but Doom will include a chunk of OG Doom in each of its levels. They won't be easy to find, though: “You gotta look carefully. They're really hidden away,” Stratton says in the video. “We don't give a lot of hints to where they are, so I think people will have a good time finding them for themselves.”
Doom will be out on May 13.