E5M1: Welcome to your Life
Walk around to the front of the store, and enter through the front doors. Walk to the back of the store, and turn to your left. You'll see the Eye key at the far end of the store. Get it, then go up to the 2nd level of the store. Enter into the Manager's office on the right side of the store. Turn to your left and jump up on the drawers, then into the attic. In the attic, you'll find a metal door. Opening it leads you out to the roof. Walk all the way to the end and turn to your left, and you'll see the Skull key. Get it, then jump down from the roof.

You'll know be about where you started the level. Jump over the crates, and walk all the way to the end of the alley. You'll see the Skull key door to your left. Enter into this storage area to find the Moon key. Keep walking through the storeroom, and you'll find yourself at another Skull key door. This ones leads back into the store. Go up the ramp to you right, and get back up on the roof through the attic entrance in the Manager's Office. Walk across the roof, and enter into the Moon key door to your right. Push the symbol to end the level.
E5M2: They are Here
Walk out the opening room, jump down, turn to your right, and walk down to the end of the alley. Turn to your right and enter into the building. Following the passage until you get into a larger room, then take the exit to the right into a courtyard. Re-enter the building under the sign "Insmouth Corporate Plaza." Directly across from the phones is some stairs leading up. Follow the corridor, and you find yourself in a room with some steps.

Climb them, and follow that corridor to the Pub and Grill. Exit the building to the door to your left. Outside, you'll see the Fire door behind some Fire pods, turn left, and walk along the side of the building you just exited, and and re-enter the building through a different doorway. Walk down the corridors, descend the stairs (Watch out for the Gargoyle statues), and grab the Skull key. Retrace your steps to the Fire door, open it, and press the symbol to end the level.
M5M3: Public Storage
Walk forward, then take the first left turn, and walk (making your way through the crates) until you get to the wall. Turn to your left and you'll see the Skull key door. Walk toward it, turn to your right, and you'll see a wooden door over toward your right. Enter into the room and make your way to the Dagger key door. Blow open the vent to the right of the door, then use the crates behind you to jump into it. Follow the vent (ducking when you need to), and at the first fork, go right. Blow out the vent, and jump in the room, collecting the Dagger key in front of you.

After getting the Key open the door to the right of the vent, and take the lift up. After exiting the lift and turn right. You'll see a room with a switch to your right, and a wooden door up ahead on your left. Push the switch to open the large doors through the window, then go back and enter into the wooden door I just mentioned. You'll see a manager's office on the ledge across the way, which you can do by jumping on the boxes over toward your right. Jump over, enter the office, and grab the Skull key. Jump down from the manager's office, and make your way forward and to your left, until you come to a ramp. Go up the ramp, and through the large doors you opened just a little while ago. You can now use the crates to jump to the small Skull key door across from you, or enter in through the large Skull key door on ground level.

 Regardless, you'll soon find yourself next to some large metal doors and a conveyor belt of some kind. Push the switch next to the large metal doors, then open the metal doors, and enter the room. Cross it, and open the wooden doors ahead of you to find the symbol to end the level.
E5M4: Aqueducts
Make your way around the crates, past the "Stay Out" sign, and find the switch in the next area. It won't work until you turn the power on, so turn to your left, and go down the ramp. Blow up the TNT barrel on top of the machinery, and get the Diving Suit. Now, break the window, jump into the pool of water, and follow either one of the underwater tunnels. When you get to a fairly large area, swim up into the control near the top of the room.

Quickly push all three buttons to turn the power back on. Now retrace your steps to the switch that didn't work earlier. Hit the switch, and go through gates that open up. Jump down into the water, and make your way around the underwater area to retrieve the Skull key. After picking up the keys, look around a little, and you'll find a passage (facing the key, it's over toward your right). Follow it along, and surface into a secret area. Push the button to open the wall. Walk through the newly opened wall, and walk across the walkway to your right. Hit the switch, wait for the room to rotate, and walk across the walkway to the Skull key door. After going through the Skull key door, follow it along until you get to the room with the Electrical beams. Go through them, and enter the passage on the other side. After you climb some stairs, you'll come to a switch. Hit it, and the stairs you just climb will flip. Now climb up the stairs again, follow the passage, and get the Fire key. After you get the key, turn around, and jump down on the left side. Go up the ramp, and you'll soon find yourself back in the spinning room (use your auto-map if you get lost).

Hit the switch, and head toward the Fire key door--it's at the other end of one of the walkways. Go through the Fire key door, and through the door on the other side of the room (remember to open the cabinet next to the door to get another Diving Suit). Smash the window to your left (wait a moment and the cultists will do it for you), jump onto the ship, run straight across, and jump off the other side. Turn around, and blow the crack on the side of the ship. Once the explosions subside, jump back onto the deck, and go through door. On the other side of the partially submerged room, you'll find an underwater passage. Go through it, and you'll find a large wooden door on the right side of the next room.

Go through this door, grab the Spider key (and the Diving Suit behind the crates), and go back through the door. Go forward, and around the corner, you'll see the Spider door in this room. Enter it, and get the Moon key. Now retrace your steps to the Spinning room. Take the other walkway to get to the Moon key door. Hit the switch, and go through the newly opened door. Follow the passage along, and jump in the water. Go with the flow, and hit the underwater symbol to end the level.
E5M5: The Ruined Temple
Swim into the next area, and surface. Jump onto the pier, and enter the building. Go through the doors to your left, and follow the stairs up. After going through a couple of doors, you'll find yourself in an outdoor area (take note of the other wooden door here, we'll be coming back here later in the game). Just as you enter this area, turn to your left, and walk forward until you come to a dead end. Just to the right of the dead end, there's a doorway.

 Go through it, and follow the passage around until you get to a ledge that surrounds another room. Jump down, and follow the passage to a room with this giant thing in the middle of the room (any guesses on what this is supposed to be?). Pick up the eye key, and leave the room the way you came in. On the right side of the passage, you'll find a room. Enter it, and take the ramp back up to the ledge where you had just jumped down from. Turn to your left, take that passage around, and you'll find yourself back outside with the Eye key door in front of you. Enter it, grab the Fire key, and find your way back to the wooden door I told you to take note of earlier. Enter it, go through the Fire key door, and push the symbol to end the level.
E5M6: Forbidden Rituals
After you go through the wooden door, go over to your right, and collect the Dagger key. Use it to go through the Dagger key door in the same area. Go forward, and go through the small wooden door to your left. Shoot the X-shaped beams, and drop down. Jump down into the pit. Follow the passage, shoot your way through the grate which blocks your way, and keep following the passage until you get to the caged zombie.

Pick up the Moon key, and take the lift up. Follow the passage along until you get to the forbidden ritual with the pool of red water in the center. From here, you'll see the Moon key door. Shoot the symbol above the Moon key door, and the wall to your left will open up to reveal the exit to the secret level. The regular exit is behind the Moon key door. Just take the lift down to get to it.
E5M9: Forgotten Catacombs
Go around the corner, and activate the switch to call the lift down. Take it up (note the Skull key door to your left), and follow the passage to your right to the Skull key. Retrace your steps, and go through the Skull key door. After you go through a metal door, you'll see a wooden bridge leading the Eye key door on your left.

Underneath the wooden bridge is the Eye key, jump down, and grab the key. It shouldn't prove to be too difficult find your way back to the Eye key door. Go through it, across the wooden bridge, and down the ramp to your right. Go through the metal door, grab the Fire key, and go back up the ramp. Keep going forward, and across another wooden bridge to the Fire key door. Go through it, and push the symbol to end the level.
E5M7: The Dungeon
Set the symbols in front of you to Spider, Dagger, Moon (you'll see these symbols next to the doors that open). Go down the now opened passage to your left. When the floor falls out beneath you, turn around and push the panel that will eventually be revealed. Turn around, and enter the door that just opened. Go up the stairs, and enter the room in front of you with the two Gargoyle statues. Over to your left, you'll see the Dagger key. Jump down, grab the key, and enter the doorway underneath where the two gargoyle statues were (Hmmm, wonder what happened to them?). When you get into the room with the stairs behind you, take them up. When you get to the top, two walls will open up one at a time. Kill everybody, and hit the switch in one of them (the first of three), and another wall will open.

Enter the teleporter in it, and you'll be teleported to a room next to the starting position. Set the symbols to Dagger, Spider, Spider. Enter the newly opened door in front of you. To your right, you'll find a small room with a lift. Take the lift up, and follow the passage around (take note of the Skull key door), and you'll soon find the Skull key. Retrace your steps, and go through the Skull key door. Hit the switch (2nd of 3), and retrace your steps back to the starting room. Set the symbols to Moon, Fire, Dagger. Enter the newly opened door to your right, and find your way to a wooden door. Enter it, push the switch, and leave the room.

A newly opened area will be over to your left. Enter it, and pull the large wooden lever. Head back toward the starting room, and you find a newly opened passage (you can't miss it, you're going to be attacked from it). Go into it, and walk all the way forward, around the corner, and up the stairs. You'll eventually get to the room with the Moon key. Grab it, and jump out the window. Go through the Moon key door, and push the final switch. Go back outside, find the stairs, and find your way back to the starting room (use the auto-map if you get lost). You'll find that another door has been opened up here, and follow it to the symbol that ends the level.
E5M8: Beauty & the Beast
Kill all the Priests. When they're all dead, a wall will lower in the center of the map to reveal the symbol to end the game.