First, even if you are an experienced HEV suit user, you should avail yourself of the Hazard Course. It teaches you how to use the suit (the equivalent of armor in other games) to its fullest advantage, and that special long jump module could save your life.
Second, as Black Mesa deals with a wide variety of "special" experiments, it is important to remember that many useful items are stored in the plethora of wooden crates and containers throughout the lab. Smash 'em all and look inside-but avoid the ones marked "Explosives" if you know what's good for you.
Third, remember that the guards and scientists are your friends; they can watch your back, heal you, and even get you out of a sticky situation. Often, if one dies, you cannot continue. Save early and often.
Chapter 1: Anomalous Materials
This is mostly cinematics, an intro that sets the mood and is pretty
cool in its own right. Not much to do, though. After the intro train ride,
explore the lab a bit, talk to people, find your (Gordon Freeman's) locker,
the HEV suit, then proceed to the test chamber. In the test chamber listen
to your instructions, and follow them to the letter. Then watch as all
hell breaks loose….
Chapter 2: Unforeseen Consequences
Now you're into the game proper. Use the sputtering retinal scan device
to get the door to open slightly. As you make your way out don't miss the
crowbar on the floor (you will need it). You will need to have a scientist
follow you to activate the next retinal scanner.
In the main lobby go through the hole (smash the vent) to enter the
next room. Proceed to the area with the hound-eye beasts (they look like
Smithfield hams with legs). Find a square vent hole leading downwards (to
save health, kill the zombie on the other side of the bars first). Enter
the sewer, find the other square hole vent (in the ceiling this time) and
the valve. Turn the valve, which floods the tunnel, swim up through that
second hole.
On the descending platform dodge the falling head crabs by moving side to side. Later use ledges to avoid the falling floor pipes. And you can use the crates to make a bridge in the water, or just swim around until you can ascend on the other side.
Chapter 3: Office Complex
Avoid the dangling live wire and use the vent to enter the room with the scientists (watch out for the 'fisher-tongue' critters on the ceiling). There is an electrical room, and you can shut off the power there. Exit through the door and now you can safely bypass the live wire.
When you find the guard in the little control room, try and save him by killing the zombie who attacks him. Do it fast enough, and he'll survive to let you in, where you can pick up a shotgun, some ammo, and other nifty toys.
In the flooded room turn the power off with the light-switch, making the water safe to navigate. Open the vent and exit the room, but beware of the fan blade in the vent shaft (duck to proceed).
Guards make good diversions for the annoying head crabs and security guns you'll find on the stairs. Proceed to the freezer….
Hit the red switch at the far end, and use the ladder to enter the duct system. Jump onto the moving platform from the upper levels of the shelves, and move on through the vent.
The elevator is out. Make a running jump and push 'up' to grab and climb
the ladder. Continue moving around the shaft climbing ladders until you
reach the top of the elevator, and break the vent with the crowbar to drop
down.
Chapter 4: We've got Hostiles
Jump or duck to avoid the red or blue trip lasers (red activates sentry guns, and blue sets off nasty explosions).
Fight the soldiers, but if aliens are around, let them kill each other. Beware flanking tactics and grenades from the soldiers (they are very smart). Continue on until you can take the elevator to the surface.
An Osprey drops guards on the surface to massacre you. Kill all on the ground and make for the bunker (if you wait, the plane airdrops more, and more…). Don't hesitate, explosions are constantly rocking the ground and will eventually get you if you dally.
In the vent system avoid the fan, kill the soldiers, and use the middle vent (the other two go nowhere) and find a computer panel; activate it to exit.
Chapter 5: Blast Pit
Find the train/tram, jump on it and hit 'use' to activate it (forward
makes it go faster). Best of all it runs down a lot of the monsters in
the tunnel. Note: at full speed the train will break through the barrier
and send you flying (not necessarily a bad thing as you can still continue
providing you can afford the health), use the boxes to climb past the slime
to the pipe.
Continue on and see what is happening at the Test Fire Chamber. Its not a pretty sight, but that horrible monster needs to be killed… how convenient that it is sitting under a rocket engine. To fire the engine and kill the critter, you must provide oxygen, power, and fuel. To do this you must get past the tentacles….
You have two choices: you can walk and crouch past and descend to the various hallways that lead to the controls rooms, or you can use grenades or shotgun blasts to cause the tentacles to retreat briefly (then you run for it, repeating the blast at every platform). When going after the oxygen, fuel and power switches, remember: the order is not important.
Oxygen & Fuel switches: Go down to the level directly below you, and break the boards with your crowbar to exit the chamber. Cross the bridge (hint: don't shoot at the alien on the bridge, those boxes explode and will make you have to jump across) and follow the red and blue pipes down the hallway. Break the sewer grate and drop into the pipes, follow the pipe and turn left, then climb up.
Approach the huge fan and before pushing the button you'd better save the game (this is dangerous). Hit the button and run up the ladder hopefully avoiding the fan blades now in motion. Once the fan hits full speed jump toward it and ride the air current up to the boarded up ceiling (use your crowbar to break them). Use the vent to get to the Oxygen/Fuel control room and activate both. Exit by using the ladder and head back for the test chamber and the giant tentacle monster.
Power switch: Descend to the lowest level, avoiding the tentacles as you did before (explosives or skulking). The walkways have huge holes in them and these jumps are tough, save first. It helps to look downward to time the jump better.
Once across you will see a huge puddle of water on the floor (this will become electrified soon, so you might want to arrange the boxes to form a bridge now) move across it and enter the room. Avoid or kill the fisher/tongue creatures that hang from the ceiling and activate the elevator with the button.
Look to your right when it arrives; see that ladder? As the lift descends, but before it breaks and falls, make a flying leap for that ladder. Descend the ladder to the radioactive goo and piping. Walk on the pipes to avoid damage. Find the generator room and activate both switches (do not do this while on top of it though, or you'll become all dead and crispy). Watch the spinning platform to get the timing right and exit the generator room safely. Climb the ladder again, and look for a platform to jump to.
Once you reach that puddle again you will either have it easy (you made a box bridge before hand) or hard (you didn't); the electrified pool is extremely damaging. If you have set up the boxes, cross using them. If not you can move two crates to form a bridge most of the way, but it will still cost you around 20 health to make it across.
Now that the oxygen, fuel, and power are on, you can make some fried calamari by ascending to the top and hitting the now active test fire button. Watch the tentacles go boom (you won't take damage if you back away as far as you can go away from the window, but you'll miss a pretty explosion).
Exit through the hole once occupied by the tentacle monster. Fall through the center or you will die by hitting the slanted ground first. Grab the .357 magnum at the bottom of the pool. Swim around until you find a broken pipe to swim through, walk on the pipes until you reach one suspended by cables.
Look across and see a very hard jump to an opening with a broken grate. Make the jump and beware, the pipe ahead will break (note the wall discoloration); if you fall with the pipe you will perish, so jump back as it falls. Use the small ledges on the sides to make a controlled descent into the room. Kill the head crab under the table and collect the power-ups.
CHAPTER 6: Power Up
Through the tunnel you come upon an open area where there is a massive firefight going on. A gargantuan armored alien beast is making short work of a handful of the government's best and bravest. They don't deserve your help; after all, haven't they been trying their best to perforate your geeky skin? Make a break for the open passageway (across from you, behind the beast) as soon as you can. Waiting for the soldiers to die just makes the beastie gun for you (not good).
When you reach the red doors, find the valve-wheel, turn it until the doors open and climb up through the opening. Follow the signs to the Power Generator (signs mark the route). Shoot the trip mines below you, or simply send a detpack (those explosives you may have found) down the elevator without you.
After the elevator take the stairs down to the bottom, enter the flooded room (watch out, those fish-things pack a tiny bite, but you can kill them with your crowbar) and destroy the boxes obstructing the generator. Climb up one level of those stairs to turn on the fan. Then head back to where the gargantua is waiting (by now all the soldiers are dead). Rush past the beast and go immediately to your left down the corridor. Find the switch, and then head back to the corridor you that you just came from.
You need to find the track control room. You'll find it by going up and leaping across the hole. There is a wounded guard there who'll talk with you a while — if you like. Turn on the power and the beast will eventually walk into the electric stream and die. Or, before you do any of this you will find that monster killable if you use explosives. Grenades, detpacks, — whatever you got so long as it goes boom. Frankly, though, it's not worth the ammo. Fry him.
Ride the train to the middle of the room, go back to the track control room and use the switch to turn the train to the other track. Then ride the train through the boxes.
Chapter 7: On a Rail
Tips for the enormous train areas:
Shoot the arrow-signs to switch the track. Stop the train whenever
you find an area with monsters, doors, or ladders. It is much more dangerous
to go through this area without the train (but it can be done) as the water
and train rail are electrified. Look for switches, boxes, sentry guns,
and monsters. If you seem to be going in circles on the train find an arrow
sign to shoot so you switch tracks.
When you come upon soldiers using mounted rocket launchers get off the train, crouch, and use your big weapons to fry them. The rockets pass harmlessly overhead if you are crouched (the train can protect you from these as well, simply crouch and speed by them, but you will sometimes miss power-ups).
Finally, after much rail travel, you will come upon a nasty situation. A huge bunker with a cannon in it, a machine gun nest on the left, and an open area with lots of soldiers around the corner. Use a grenade to take out the machine gunner, and hide behind the boxes to avoid cannon-fire. You can push the boxes ahead of you to get in closer to the bunker. If you are lucky you can run past the bunker, into the corridor, guns a'blazing and hope to take out the soldiers fast enough. But you can buy yourself a little time to snipe if you take out that cannon. Rush it, climb atop it, and drop a grenade or detpack into it is one way. Or throw grenades at the top and hope you get lucky by killing the gunner.
Now you come upon a staircase, with lots of red-laser trip mines. Since there are no sentry guns you may figure you can jump these safely. You thought wrong. See the explosives lining the walls? What you need to do is push the boxes under the second laser, run back and up the stairs, moving under the first laser (crouch). Then jump onto the box, then over the last laser and to the door. Watch out for a couple of soldiers nearby.
Move along until you find the launch controls. Launch the rocket, and
stay at the window for the show! Remember you have to exit the way you
came, which means avoiding the trip mine staircase!
Chapter 8: Apprehension
Get on the train and start her up, you are in for a hell of a ride. You get the opportunity to get off the train before it crashes, and you can do that, but you can also ride it all the way down the hole into the drink. Swim to the bottom of the pool and release the crates down there, when they float to the surface you can use them as a bridge to get to the other side corridor.
Lots of swimming, lots of searching, but soon enough you'll enter a large room with a pool and a suspended cage. Climb up to the top of the cage and grab the crossbow before descending into it. Use the switch to drop the cage into the drink. Kill the LARGE fish monster with the crossbow (the 9mm pistol also works —none of your other weapons work underwater… except the trip mines, which make for a satisfying, but difficult, kill).
If you are fast you can skip the fish, but it is much easier to open the grate and leave the room by killing it first.
When you reach the large control room with the three huge pistons you have to turn them on, and then jump from one to the other to reach the suspended catwalk. Kill all the monsters and then the scientist will let you into the room. He tells you there isn't anything but danger in the cold room (believe him) and run like mad through it (the cold does damage) until you find the ladder that leads out.
After the nice guard gets assassinated mid-sentence you will have to face one of the greatest enemies a 3D action game has given us. The leather clad sniper/assassin girls. These quick moving targets are best dispatched with the crossbow from afar (use zoom mode) or by relentlessly chasing them through the room with the machine gun or shotgun blazing. Once they are all killed (there are three), you can move up the catwalk to the platform and use the wheel to open the door.
There appears to be no way to avoid what happens next. Gordon gets captured by two sadistic guards who figure its better to kill him and hide the body than deal with the paperwork. So they place you in a Batman TV series (the Adam West 60's version) deathtrap, and then they don't wait around to see if it works.
No weapons, but you still have your HEV suit and the walls start closing in on you. Carefully but quickly, climb the crates to the ledge, wait until the walls close and use them as a bridge to the other side. Grab the crowbar and break open the grate to leave the room.
Chapter 9: Residue Processing
Lots of traps, noxious gasses, radioactive mess, and danger in this
sprawling jump-fest of a level…
BASIC TIPS:
Save often, jump carefully, and time your movements through moving
machinery well.
When you reach the large vats use the plungers to make it to the other side. Duck under the grinding wheels. Upon reaching the control room note the conveyer belts and the massive pounders, move all three switches to the up position and go and press the green button. Don't dally, they pounders don't stop for long, run up either conveyer.
Jump from conveyer belt to conveyer belt until you see two conveyers side by side, get to the one of your left. To get rid of the nasty trip mine around the corner you want to drop a detpack on the belt, wait around five seconds, and detonate (be sure to backpedal to avoid the blast).
Chapter 10: Questionable Ethics
Shoot the electrode switch on the fence to open the door. Once inside
note the terrifying monster behind the glass, take a deep breath, then
break the glass over the switch, and press the button. Fight the monster
with whatever weapon you wish but note the armored areas, only fire into
areas that give you that yellow-green blood reward.
Run around and try to let the monsters fight the soldiers for you, once the battle is over pick off the survivors. Find four rooms with switches and turn on all the lasers. Then find the room with the sign that says "Do Not Obstruct Laser Shield". Move the box underneath the laser and then press the button, which lowers the shield and the box obstructs it from blocking the beam. The beam burns through the wall and you have your way out… but be sure to pick up the funky gun from the scientists in one of the other laser rooms before you leave.
Chapter 11: Surface Tension
A situation like this isn't pretty. You have a dam in front of you, with a bunker shooting bazooka rounds, a long drop off to one side, and a pool of water with a vicious monster fish on the other… oh, and don't forget the lethal attack helicopter circling above. You can destroy the chopper but it is extremely difficult and not really worth the effort. Head immediately into the water, and up the ladder to the tower on the far side. Try and keep the tower between you and the chopper, also beware the snipers on the dam; head inside and pull the switch. Jump back into the water and kill the fish, or avoid it. Make for the wall of the dam and find the red wheel. Turn it and swim through the open grate.
In the next clearing you'll find another seemingly bad situation, a
familiar looking tentacle monster guards some ammo and power-ups (again
a grenade will buy you time to grab it, but it isn't necessary), the attack
chopper is still tracking you, and these odd bulges in the ground keep
sending head crabs your way. Best to head over to the small hole to the
right. Watch out… there is a mine field beyond.
Use grenades or your machine gun to detonate the mines before proceeding.
Continue on until you find a red wheel to turn and then head back to the
now open grate. Be careful, this fall will kill you… use the ladder to
descend.
This next area, an open area of pipes, canals, and sand bunkers, displays Half-Life's brilliant soldier AI perfectly — much to your chagrin. The best way to handle this situation is to climb up the ladder, pop up fast like a gofer, use the crossbow or .357 magnum to quickly dispatch nearby soldiers, and pop back down fast. Move quickly, as the soldiers will soon begin sending grenades down all nearby holes. Repeat this process with as many of the pipe tunnels as possible. As far as the tank is concerned — the laser guided missile launcher is recommended, as is jumping on it and dropping a couple detpacks. Strafe and try to use grenades or missiles to destroy the next armored vehicle, which while somewhat lighter than the tank is no less deadly.
In this area proceed cautiously. Avoid trip mines and land mines, and watch out for snipers (two of them) in the windows (a rocket or grenade works wonders here). Blow up the barrels to knock out the power and crawl under the barbed wire to get to the fallen power lines. Climb to the roof and jump into the hole.
DO NOT SET OFF ANY TRIP MINES IN THE NEXT AREA! Why? Because there are a couple of nukes in the warehouse and some idiot decided to trip mine the entire area. Be careful when moving crates as some of them can pass through, or are connected to, trip mines. The easiest way to handle this tense situation is to turn your computer off — just kidding. Find the crate that rests on a simple lift and destroy it. Push a crate to the stairs and jump over the laser line, enter the control room carefully and activate the lift (if you didn't destroy that crate… boom). From the lift at its highest position jump into the central area and descend to safety.
Around a corner you'll find some big aliens; let the soldiers take care of them for you. Round the corner and kill any survivors and strafe to kill the tank. As you continue, watch out for a sniper in the window as you round the second corner (this sniper can make continuing impossible if she kills the nearby guard). Go up the stairs and find the guard. Have him open the locked storage room for you, and grab the power-ups. Go through the window and leap to the opposing ledge. Climb up on the roof and drop down to take care of any opposition. Then climb back up and proceed to the opposite hallway (use the rafters).
The next clearing features more of those hornet gun armed aliens and a circling transport regularly dropping troopers. Let them fight it out while you make a dash for the tunnel. Move through the tunnel until you reach the alley where you left that guard you needed to open the locked door. Enter the room, grab some health from the station and move up the stairs and up to the big cannon. Use the cannon to kill any soldiers and blast open the big door you can barely see to your left.
Whew! Use any of the mounted machine guns to clear the waves upon waves of aliens coming at you and use the 'bounce crater' trampoline to jump the wall. Break open the grating and beware the insect-things (called snarks). Kill or avoid them (they self-destruct after around 25 seconds). Enter the shaft, kill the soldiers in the next room, and use the tank to kill the aliens that appear. Use the mechanic's lift to exit the room , then use the bounce crater to get to the next area.
Now use the green map to call in airstrikes to get out of here. Call one on the wall across the moat, the fortress door, and the tower before you. Climb across the moat on the fallen tower and you are done.
Chapter 12: Forget about Freeman
No real puzzles here, just a lot of enemies and killing — have fun!
As the ceiling and walls come down try to climb up and through the newly created hallway. Proceed and fight your way through. Hint: You can avoid the tank by running like mad to the elevator. Watch for ambushes, sentry guns, and trip mines.
Chapter 13: Lambda Core
After the snipers are dispatched kill all monsters you find. Once finished the scientist opens the door; grab the big experimental gun he's been building. Activate each cooling system switch and enter the water, swim to the reactor and activate both switches. Climb out and hurry as the reactor begins shooting lightning.
Time it correctly to use the teleporter to get yourself inside the core and on the rotating platform. Jump across to each door in turn, then up to the next level of the puzzle. It's challenging but fairly obvious once you get a good look at it. Once finished open the door and meet the scientist and the guard, listen to their story and grab everything they offer you.
Once the process for activating the big teleporter (that allows you to bring the pain to the alien world) starts, try and kill the flying aliens as fast as possible… don't let them kill the scientist opening the 'porter. Once he says go… you'd better hurry.
Chapter 14: Xen
Welcome to Half-Life Super Mario style. Use your super long jump ability to go from floating platform to floating platform, and don't fall. If you see a pool of water from now on, stand in it and it will slowly heal you.
In the big chamber on the center island 'use' each of the strange mushroom things, then break the webbing imprisoning the floating lights (butterfly things). They each go to an open mushroom and activates the teleporter.
Chapter 15: Gonarch's Lair
Head crabs have to come from somewhere right? Ugh, she is a bad momma. Aim for the egg sack on the bottom of this exceedingly strange monster. If it releases pupae versions of the head crabs, use the hornet gun on them. Once Gonarch runs away follow her to the next area and keep fighting, while trying to stay alive. If low on health try and get to the hole and drop down to the ledge below, watching for adult head crabs. In the tunnels down there you'll find some ammo and a healing pool. Then use the bounce crater to re-enter the fray.
After you do enough damage a third area opens up and you fall into a pit. Fire at the sack repeatedly until Gonarch drops down with you. Then hide behind the strange tree things until you eventually kill her. Note that you can, if careful, avoid being sucked into the pit until you're good and ready. Toss some grenades and det packs in on top of old Gonarch to soften 'er up before getting up close and personal.
Chapter 16: Interloper
Look for a yellow colored area inside the cave, remove the webs and ride the white tower elevator to the top. More jumping, just like in Xen, but this time it's much harder. Jump from floating rock to floating rock until you come within range of those strange winged bird things - jump on one of them and ride its back to the teleporter.
Use a grenade or walk slowly past another tentacle monster and proceed to the next teleporter. Once you enter the factory you'll see why those lightning spewing beasties are called slaves --kill them if you like, but they won't attack you. The fliers are what you need to worry about. Take the lifts to the conveyers and enter the one that doesn't have a blue forcefield. In the next area avoid destroying the large barrels… they contain hornet toting aliens with a bad attitude.
Enter the red vents to find a large room with spinning cog-like lifts, ride them all the way up to another teleporter.
Chapter 17: Nihilanth
Welcome to the end boss… watch out, he may look like a big baby, and he is quite cranky, but he has powers that will annoy the hell out of you. Avoid the lightening balls he throws, but most of all use the rock formations as cover when he tosses a green energy ball. These teleport you to the most annoying mini-levels you'll face.
The idea here is to destroy the three triangles. You have to use the bounce craters to get high enough to nail the last one and then start shooting at Nihilanth's big ole head. After enough hits his head opens up and you need to send a couple detpacks, grenades, or yourself inside there to destroy his brain. Good luck, you will need it!
Once the big baby is destroyed you are treated to a wonderful cutscene
featuring that suited character you may've seen. He sheds much light on
this affair and gives you a choice of outcomes for the endgame. I won't
reveal these to you, though; after all, you have to do something for yourself!