Easter eggs in video games — a subtle nod to developers, the history of the series or a hidden in-joke — are always welcome surprise nuggets of fun tucked away for gaming sleuths to discover. With the new first-person shooter Doom set to arrive in a few weeks, id Software has shed some light on cool new Easter eggs hidden in each level that should be exciting to long-time fans of the series.

In a livestream with IGN, Doom creative director Hugo Martin and executive producer Marty Stratton revealed the "uber secret" hidden throughout the game.

In each of the game's single-player levels, players will find a hidden lever. Once activated, a jingle will play and a door will open that will transport you to a slice of a level from the original 1993 game and its sequel. These hidden sections feature the same graphics style, textures and even music straight from the original maps but allow players to use the weapons from the reboot.

"You get to play them with new guns and new demons but you'll notice that in the ones that include demons, they're actually in the right places," Stratton said. "We have classic pickups [and] some of the classic music is included in a few of them."

These throwback Easter eggs vary in size, ranging from a single room to larger stretches of the classic levels.

Stratton also adds that once you have located all these hidden levels, you will unlock the full version of the map that can be accessed from the game's main menu to play as one big level.

"You gotta look carefully. They're really hidden away," Stratton said. "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 is slated for release on 13 May for PlayStation 4, Xbox One and PC.