The Tentacles rely on sound to locate the player.
In order to fire the rocket engine, the player must restore the power, oxygen, and fuel which requires the player to get into the inner chamber of the silo to reach other areas, while avoiding the Tentacles. Here, there is a dying scientist tells Gordon to fire the rocket engine to kill the Tentacle creatures before they grow any larger. Inside the silo, there are huge Tentacle creatures, who act as boss characters. The chapter starts in an abandoned rail tunnel that leads to the silo. According to the strategy guide, the Marines haven't located this area yet, which explains the lack of human enemies in the chapter. He can reach there by going through the decommissioned rail system beyond the silo complex. In the previous chapter, a scientist tells Gordon that the science team at the Lambda Complex might be able to end the catastrophe. For the the game's full story, see the Half-Life storyline article.
