Like Wolfenstein before it, Doom 2016 has a particularly lavish kind of Easter egg: classic levels from the original Doom and Doom 2, recreated in the new engine in all their original low-resolution-texture, low-poly glory. They're a lot of nostalgic fun to explore, and there are no less than 13 - one in each level of the new game.
To unlock a classic level, you need to first find a hidden lever and pull it. A chime will sound and a door, hidden elsewhere in the level, will open, leading to retro game heaven. We've got the locations of both the levers and doors below.
Level 1: The UAC
- Lever: After opening the blue gate and down the path to the left, keep to the left and down below you you'll see the top of a yellow cylindrical structure with a fan inside. Drop down below it, enter the gap in the fenced-off area surrounding it and pull the lever.
- Door: From the lever, head right to find the door.
Level 2: Resource Operations
- Lever: After restoring power and dropping to the lower level, follow the walkway round until you find two large crates. Clear the area of enemies and then climb onto the crates, up onto the narrow walkway above (where the armour pickup is) and make your way along it until you're near the large screen. Stand on the left handrail and jump up to a small ledge, then climb up to find the lever.
- Door: The secret area is directly below you, so drop back down the way you came and head under the screen to find it.
Level 3: Foundry
- Lever: From your starting position, jump the gap to your left, cross the bridge, turn right, and head halfway along the next bridge. On the left is a square platform, and the lever is on the edge closest to the lava flowing down.
- Door: From the lever, carry on across the bridge and the door will have opened behind the small lava flow.
Level 4: Argent Facility
- Lever: Head up the slope from the rune trial, and the lever is behind some barrels at the near end of the platform to your left.
- Door: The door is on the right side of the room with the pentagram on the floor shortly after pulling the lever.
Level 5: Argent Energy Tower
- Lever: After one of the arena fights in the tower you'll ride some cargo drones up to the next area. Find the one with the blue lights and the lever is at the top of its journey.
- Door: Ride the drone back down, get off and wait for it to head up again, and head into its hole to find the door.
Level 6: Kadingir Sanctum
- Lever: In the area where you first meet the Barons of Hell, there's a dark tunnel on the opposite side of the area from the exit, and the lever is at the end of the tunnel.
- Door: From the lever, head towards the exit. Before you get to the door, drop off the left of the stone bridge and the classic door is underneath.
- Lever: After exiting the lab, killing the Cacodemon, and jumping across to an upper platform, check behind the cargo for the lever.
- Door: From the lever, drop down to the area with the pillar with a big number 1 on it to find the door.
- Lever: After lowering the cargo forcefield, make your way round to the pipe but jump onto the ledge above it. Jump across the rocks to the left and onto the pipes, then drop down to the metal platform below.
- Door: Make your way from the lever back to the previous gore nest area, and the door is in the far wall.
- Lever: When you reach the circular room after activating the Helix Stone, turn right at the bottom of the stairs into the first candle-filled enclosure, and the lever is in the right hand corner.
- Door: Drop into the pit in the centre of the room.
Level 10: Titan's Realm
- Lever: After opening the yellow gate and clearing the room beyond, ride the weight up and activate the skull switch. A secret alcove containing the lever will have opened to the right of where you entered.
- Door: Pulling the lever will re-open the passage you entered through. Head up the steps, turn right, and then turn right again at the bottom of the steps into the next room to find the door.
Level 11: The Necropolis
- Lever: After grabbing the yellow skull, head for the alcove to the right of the teleporter to find the lever amongst the flames.
- Door: Double back, and it's to the right of the Argent Cell.
Level 12: Vega Central Processing
- Lever: In the storage room in Sector P Access, behind the crates that the elite is leaning on.
- Door: After pulling the lever, double back, turn right into the maintenance corridor and follow it to the far end.
Level 13: Argent D'Nur
- Lever: Take the path opened up by the second Secret Skull Switch. The lever is just ahead of you after you climb up a ledge in the passageway.
- Door: The door is immediately to your right after pulling the lever.
Doom secrets and collectibles guide
A miscellaneous selection of hidden weapons, data logs and other secrets.
Doom - Where to find all the Doomguy model collectibles
Locations of all the action figures to help you get that 'Every Nook and Cranny' Trophy.
Doom - Where to find all the Field Drones for weapon mods
Power up your weapons by ripping mods off these obliging flying robots.
Doom - Where to find all the Elite Guards for Praetor Tokens
They didn't die in vain - they died to afford you slightly better armour.
Doom - Where to find all the Rune Trials
How to unlock all the challenges that reward you with permanent perks for your Doomguy.
Doom - Where to find all the Argent Cells
Invaluable upgrades to your total health, armour and ammo capacity are found in these locations.
Doom - Where to find all the Automap Stations
Unexplored areas of map bugging you? These terminals will fill you in.