Doom II: Hell on Earth/MAP03: The Gantlet

Level 3 - The Gantlet
When you leave the first room, you should see a shotgun - dispatch the imps quickly, then jump off the stairs to the left to collect 20 shells. Go up the stairs on the right side of the room, and kill the enemies that you encounter. If you like, you can get the megaarmor, but be prepared to fight a few soldiers and sergeants.

When you go up the lift, you will enter the water area. If playing on Ultra-Violence, wait a bit before fighting in order to take advantage of friendly fire. Kill the enemies when they're distracted, as well as the heavy weapons dudes in the water area below. Advance across to the chaingun, and clear out the local area, which will include spectres. Head up the stairs to get the blue key and open the door to the left reach the switch. Flip it.

A bridge will be raised to a teleporter that will bring you closer to the exit.

In the final room, you should be above a small chasm. Jump in. There are a few cages that open as you move through the area. To reach the exit, you need to get the red key and go up the lift. However, a cage containing demons in the chasm will activate when:
 * 1) You enter the chasm.
 * 2) You collect the red key (or you wander around in certain locations)
 * 3) You approach the switches to the right.

To call the lift, flip the right switch. Flipping the left switch will open a small area on the other side, containing imps.

When you go up on the left, open the red door to the right, kill the demon, and exit the level.

Weapons

 * The shotgun is available at the start.
 * The chaingun is available in the darkened water area.

Shortcuts

 * From the entrance, you can straferun into the megaarmor.
 * If you can get into the secret well and into the teleporter, you teleport onto the rocket launcher. Move a bit to the side, and when the Heavy Weapon dude teleports near you, shoot him with a rocket and jump into the exit teleporter. (This is dangerous.)
 * You can avoid the central dark area with the spectres by straferunning across some water. However, it is slower than rocket jumping and can still be blocked by a single monster.

Secrets

 * In the water section, you should see what appears to be a well on the right hand side. To reach it, you have to sprint towards it from the bridge, but is possible to reach from the front platform. (This may be easier with straferunning.) Contains a supercharge, mega armor, and invisibility.

Pseudo-secrets
When you touch (but not use) the switch to raise the bridge to the exit, look to the left of the entrance of the water area. In the left water "wing" to the right of the well, you should now see an hidden door containing a backpack. (You can also reach this from a teleporter that opens near the entrance.)

Deathmatch
In addition to items normally found in single player:
 * Rockets are found in the eastern part of the map.
 * Super shotgun is next to the backpack.
 * Super shotgun + Supercharge is near the exit.
 * Plasma cannon is in the blue door behind water area - northeast corner (left)
 * BFG and a cell pack is in the well secret.

In this map, a player can dominate the map from the water area. With easy access to the rocket launcher, plasma gun and BFG, the main approach from the lift can be blocked off easily; a single timed rocket can severely harm the enemy before refiring or switching to a better weapon. The other approach, while it doesn't become available until a player rubs against the bridge button, can still be covered by a rocket, but does give a better chance for the opponent to sneak up.

The exit can't be reached without going through the water area. As such, the dominating player(s) have slightly better control over ending the map.