Quake II/Research Lab

Level objective
The objective for this level is to locate the repair facility, steal the Commander's head, then retrace your steps and return to the Outer Hangar.

Strategy
This level has a straightforward objective and a single entrance / exit through which you both enter and leave. If you find your way blocked, then you have missed something that you need to do, such as deploying a walkway or shutting off a force field. However, it is rather maze-like, having a lot of similar-looking passages connecting the various laboratories and other rooms and it is easy to lose track of where you are, where you've already been and where you need to go next. On the plus side, the twists and turns in the passages give you plenty of cover from behind which to shoot at the enemies, who, for the most part, are just standing there waiting for you and are quickly dispatched.

Wounded comrades abound and, for their own sakes as well as yours, should be put out of their misery and cleared out of your gosh-darned way. Some of them may give you any ammunition they happen to be carrying. There are a lot of Parasites, usually in pairs. There are also Medics, so watch out for their ability to revive defeated Strogg that you have neglected to gib. Areas that you've already visited and cleared of enemies are not necessarily still clear when you return to them so don't assume this. Be prepared for enemies to appear suddenly, rising from the floor or dropping from the ceiling or even, in one case, emerging from a hidden alcove just behind you.

To the Blue Key
The first room inside the Research Lab has a locked door opposite to you and a computer console down a few steps to the right. Press back the keyboard of the computer to open the locked door. You will be set upon by two Parasites, so equip a weapon suitable for dispatching them. Follow the passage beyond the door around two bends and turn back to deal with two more Parasites that emerge from a hidden alcove. There is armor in the alcove, but remember that you'll be coming back so you can safely leave it to pick up later when, just possibly, you'll need it more than you do now. Continuing around another corner, you'll see an elevator shaft blocked by a pale-yellow force field. Turning left here, you will approach a tee intersection and two Iron Maidens will slip out, one from each side, to do battle. Go to the left at the tee and through the door. There is some nasty research going on in here and you can help out, if you like, by pushing back the computer keyboards, but what will be most nasty for you are the two Iron Maidens who rise on elevators from below the floor. A U-turn in this room brings you to another door, through which two more Parasites will rush when you open it. Turn left, through a door and right into another laboratory with more gruesome experiments. Kill the Brains and push back the keyboard on the right to make the Blue Key rise from the floor. Take it and retrace your steps as far as the tee intersection. A Medic has appeared in the first laboratory and, at the intersection, the ceiling will explode and another two Parasites will drop down.

The Maintenance Bridge
Take the other door at the tee. After a turn to the right, you will have to fight another Medic and two more Parasites. Continue around two left-hand corners to a room with a glass panel in the floor. In the far right-hand corner there is an elevator. Numbers show that you are presently on level 1. Step in and push the button to go down to level 2. When you step out, you will meet a Brain and then come to an area on your left guarded by two Parasites and accessed by two openings with a pillar in between. In there is a computer console. Press back the keyboard to receive the message "Maintenance bridge activated". Coming back out, note that there is a door opposite the pillar. Remember this. Call it the "pillar door".

Turn to the left to continue and meet three Brains around a turn to the right. A turn to the left and through a door brings you to the room with the maintenance bridge in it. The bridge is made of some translucent material and below it is some kind of liquid that it would presumably be unpleasant to fall into. To the left, as you go down the slight incline, are three sort-of barrel-shaped structures and in between them are two wall buttons. You need to jump across to these from the bridge, press them and jump back. To reduce the chance of falling, jump to the buttons from the high side of the bridge and jump back towards the low side, but, in any case, save the game. On pressing the first button, you will receive the message "1 more to go..." and on pressing the second the messages "Sequence completed!" and, after a few seconds, "Forcefields deactivated". The forcefield that you have deactivated is (explain here). (See also Secrets, below.)

Go back to the "pillar door" and through. A left turn in the passage will bring you to an elevator on which the floor number is not marked. Orange lights around the opening suggest that it may have been blocked by a force field. Step in, press the button and go up. At the top (level zero?) the passage will lead around two bends to a room where a head-less Tank Commander lies on an operating table with robotic arms to the right and left. His head is on a round dais to the left. Grab the head and watch him sit up and struggle as the table rises.

Cross the bridge, turn right, left, left and through a door into another laboratory. Again, you can help out with the experiments by pushing back the keyboard on the computer and watching the effect on your comrades in the cylinders, but when you're done, continue to the other door and go out into yet another passage where you will be set upon by even more Parasites. Around another right-hand turn you will arrive at a second elevator, with numbers confirming that you are still on level 2. Step in, press the button, and it's back up to level 1.

Secrets
This level has one (1) secret, plus a bonus: A.H.D.S.S.I.B.H. bjjc
 * Adjacent the upper end of the transparent Maintenance Bridge there's a cracked bar over a holding cell. Hit it with the Blaster until the bars shatter and jump up into the cell to get a Quad Damage and Slugs from the compartment that has been opened at the back.
 * Bonus — Once you've acquired the Commander's head, just before you leave the Research Lab, note the holding cell window to the right that is now broken open.  Jump into the holding cell and follow the low passageway to the end to observe the following cryptic sequence of characters on the screen, the meaning of which will become clear in the final level of the game: