Gordon accesses the silo known as the Rocket Test Lab where Black Mesa have been testing rocket engines. On the plus side, the military haven't breached this area yet. However, something much more dangerous has nested here: a massive, stationary predator known as the Tentacle. On top of that, the area is in severe disrepair and full of environmental hazards, including a toxic waste flood in the lower levels.
In order to traverse his way through the Tentacle infested Rocket Test Lab, Gordon has to fight his way into side areas around the rocket chamber in order to reactivate the liquid oxygen and fuel pumps along with turning on the electrical power in order to work the Rocket Test. Once everything's successfully turned on, Gordon initiates the Rocket Test to kill the Tentacles, which a tunnel is revealed that the Tentacles used to dig their way into the Rocket Test Lab. Gordon uses the tunnel to enter into a toxic waste dumping area, but as he traverses through it, the pipe he's walking through breaks, which results in him falling into a new area of Black Mesa.
This Chapter contains examples of:
- Backtracking: Copious amounts, as the player must sneak back through the Tentacle's chamber at least twice again after the first pass. After fighting your way into the side areas where you need to turn on the fuel and power needed to kill the Tentacles, you then have to make your way back out of said areas and through the actual blast pit, once to go to the other area and then again to actually activate the rocket.
- Bizarrchitecture: There's an alcove
at the beginning of the chapter, containing health and power stations, which is very strange. It has no doors leading to it, with the only way to access it being a barnacle hanging next to it, something which obviously wouldn't have been possible before the Resonance Cascade. It seems to have been a leftover of map changes (pre-release versions featured a door that likely led there), but in the final version, it's just a completely sealed-off alcove. - Drought Level of Doom: This chapter gives the player much less ammo than other levels, so a good management of resources is needed (especially considering that grenades are required for getting past the Tentacle).
- Hand Cannon: The player discovers the .357 Magnum.
- Hell Is That Noise: You hear the Tentacle banging on the walls before you see it.
- Man-Eating Plant: The Tentacle, according to
Word of God. - No OSHA Compliance: While this trope is in effect all over Black Mesa, special mention must go to the SEVERAL GODDAMN LAKES of toxic waste in this chapter, in addition to a giant fan where you need to activate a switch and climb a ladder that's in the path of what's essentially now a meat grinder.
- Permanently Missable Content: Just before the Rocket Testing room, there's only one opportunity to reach the hidden health and power stations alcove by being pulled up by a barnacle tongue. If you kill the barnacle beforehand, the opportunity is lost.
- Puzzle Boss: Gordon spends most of the chapter trying to kill the Tentacle, sneaking past it several times to activate the power, fuel and oxygen before returning to the control room to fire the rocket engine above it.
- Room Full of Zombies: the room to activate the oxygen and fuel.
- Sidetrack Bonus: At the start of the Rocket Test Lab, if you get pulled up by the Barnacle tongue at the scientist who says in his dying words to kill the Tentacles before they grow any larger, you can land on a small upper floor that has hidden Health and HEV stations.
- Too Dumb to Live: The guard who tries to kill the Tentacle. The thing is a thirty-meter, armored three-headed monster, and he decides, "Pfft, what a pushover bitch, I can definitely kill this thing with my Glock".
- Unintentionally Unwinnable: At the end of the chapter, the pipe Gordon is walking through breaks and drops him in a storage room below. If you don't have enough health to survive the Falling Damage, you have no choice but to load an earlier save or use cheats to progress. The console ports rectify this by filling the room with Soft Water.
- Video Game Setpiece: The Tentacle's introduction, where it smashes through the control room window and drags an unfortunate scientist away.
- Weaponized Exhaust: The rocket engine used to fry the The Tentacles and open the path to finish the chapter.
