Quake II/Outer Courts

Armament
By this point in the game, you should have collected all the available weapons:

Unit objective
The primary objective for the Palace Area unit is to neutralize the Strogg leader's communication system.

Level objective
The objective for this level is to find a functioning Data Spinner in the Outer Courts.

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Secrets
This level has five (5) secrets:
 * 1) You enter this level in a small room with fallen debris at the back and a door out to a large open area between mountains and a building.  Climb the ledges that lead around this area and keep going until you are above the entry room.  Press the button that you will find there.  Return to the room and you will discover that a side-room has appeared containing health, armor and ammo.
 * 2) While exploring the dark caves below and to the right of the entry room in the large open area, keep a lookout for a crack in the wall.  Shoot it to open a secret area.
 * 3) In the room where you find the Data Spinner, shoot the wall ahead and to the right as seen from where you came in.  This will reveal a button.  Press it and turn around 180 degrees to find the secret.  Press the button that you will find there to extend the walkway that retracted when you came up out of the sewer pipes (however, you can actually jump over the gap).
 * 4) While exploring the palace building, you will come out of a side door onto a platform with water down below.  From the water, there is an elevator back up to the platform, a second elevator that takes you to one of the entrances to the Lower Palace level and, at the other end, a sewer pipe.  As you swim though this pipe, before you turn the corner, come up and look back in the direction from which you came.  There is a hidden room with lots of ammo, some health and the Red Key Card.  You can't get in to collect the secret until you've turned off the red force field barrier in the Lower Palace.  The Red Key Card will be needed to complete a secret / easter egg in the Upper Palace.
 * 5) At some point in the level, perhaps when you find the secret in the Data Spinner room, a cave opens in the mountainside high up over the entry room.  There isn't much in it, but to collect the secret you'll need to return to the start of the level, go around the ledges again and clamber up there using the stonework above the entry room.