This level occupies the map slot MAP11. For other maps which occupy this slot, see Category:MAP11.
After a bruising battle against a powerful enemy in the previous level, you wake up in the Worm's base. All your weapons have been taken away, and it seems like you are alone in this place.
Exit your bedroom and go the Worm's hall. The Worm is not on his throne, which is unusual... Go to the throne and its back will lower to reveal a air duct. Walk inside it, and you will come to a little room with some active machinery and a switch. Activate it and don't forget to pick up the shovel (and the energy balls hidden behind the machinery). Come back in the hall and a room with computers has opened in front of the throne. Some Ontra troopers were waiting in here, kill them. Open the door in that room and go to the next corridor. There are three doors, one on the left (which leads to a room full of goodies : an Ontra shotgun and machine gun, shells, bullets, cells, a stimpack and a green armor), one on the right (which leads to another hall with four medikits) and a big one in the middle.
Open the large door. You will see a black door on your right (which requires a red skull key) and two pillars. On your left is the entryway to a vast room with a staircase. Go up the stairs, and Romero will appear. There, he will reveal that the base you are currently in is a replica of the real thing, built in order to "test" your skills. Romero also tells you that he would like to hire you in his team, since you managed to defeat his henchman. Two skull keys teleport by your sides, and you must make a tough decision : either you take the red key and accept Romero's offer, or you take the blue one if you refuse to work for him.
Red skull key route
If you take the red key, consider the level finished. Go back to the big black door, open it and it is on to the next level, where Romero's assistant is waiting for you.
Blue skull key route
If you took the blue key, you still have some work to do on this level. Remember those pillars near the large dark door? They will lower as soon as you walk past them and reveal two Rattamahattas. Deal with them in order to advance. Now, you must basically do the level backwards and kill any Ontra that has spawned in. Go back to the hall connecting all bedrooms and the white exit door, where you will come to another machinery room with some Ontra soldiers and guards. Now that you destroyed them, go to the right and you shall go to the next stage.
In the small room with the shovel, there is a blue keycard hidden behind the crates. This mysterious key opens Gordon Freeman's bedroom (Gordon Freeman is the hero of Half-Life , a very popular FPS). In his room, the famous HEV suit is guarded by an unbreakable glass wall. To access the suit, open the secret room behind the bookcase and flip the secret switch. The glass wall will open and the HEV suit is now accessible. The object has the same effect as the megaarmor.