[9-4] E1M3: The Necropolis

From the start, head forward and left to find a grenade launcher. Turn left; you'll see an ogre behind bars and other monsters. Take the stairs leading down and to the right. Follow the passage to a bridge, then jump down. Behind where you came from, to the left of the bridge, is an alcove. Shoot the back of the alcove to reveal a hidden wall containing rockets and health.

Starting from the same bridge you jumped down from in secret #1, cross it and turn right. Follow the short passage, descend two sets of stairs, and go down to a platform. Turn to face the left wall of the passage you just descended. Enter the short corridor and proceed until you reach a shallow lake. The gold key is to your left. After taking it, turn slightly left to find a darker, textured section of the wall. Walk into it to fall beneath the water. Swim through the short passage ahead and surface. You will find a ring of shadows.

From the area with the ogre behind bars (mentioned in secret #1), take the door to acquire the nailgun. Shoot the symbol, then go down the steps and follow the passage. Traverse a series of platforms until you reach a locked door. Use the gold key (found in secret #2) to open it. Continue through the passage and jump down into slime-filled tunnels. Navigate forward, turn left, forward again, left, take the first tunnel on the right, and ascend the ramp. Open the door. Two ogres will be on platforms above you. To your right, a yellow armor is blocked by two sets of two bars. Killing the ogres above will remove these bars. Shoot the wall behind the yellow armor to reveal a slipgate. Enter the slipgate to reach the platforms the ogres were standing on, where rockets are located.