- This level occupies the map slot MAP04. For other maps which occupy this slot, see Category:MAP04.
MAP04: Megalopolis is a map for Harmony.
- Exit to the east, walk past the purple keycard, and down the lift. You should be outside.
- Go through the building to the west. It's dark, but will get you around the barricade.
- You should be in a circular road, but for now, follow the arrow. You should get into a bowling room.
- Exit the bowling facility to the left. You should now be outside the central building with a newly opened door.
- Enter this building, and go to the north end of it. Press the switch to open the path to the northern docks.
- Head to the northern docks. Note that there will be a centaur on this path, and it is rather dangerous. When you are at the tocks, enter the crane and use it to board the boat. Enter the cabin and collect the yellow key.
- From the docks is a yellow key door. Enter it, and proceed through the rooms. You may find a door to the west leading to a hockey arena with some ammo. Otherwise, continue south.
- In the dark building to the south, take the path west. The stairs circle around in a loop, but will lead outside to the southern part of the map.
- In the south section, head east to the large chapel. Climb the spiral structure north of the building, and enter its roof. Flip the switch inside to open a door.
- This door allows you to get the purple keycard'. Go through the door, climb the ladder to the left, and make a right turn to the car pileup. You should be outside the mutant zoo.
- Enter the building on the left. In the left corridor is a switch - press it. Collect the green keycard in the right corridor.
- Go to the exit. While it reveals a Phage, you are free to run past it if desired.
- At the entrance, climb the crates and collect a grenade launcher.
- After walkthrough step 3, you can head behind the bowling area (which may trigger a crusher if you approach head on). On the left is a door that can be opened, and it leads to an entropy thrower.