Half-Life is a first-person shooter that requires the player to perform combat tasks and puzzle solving to advance through the game. Unlike most of its peers at the time, Half-Life used scripted sequences, such as a Vortigaunt ramming down a door, to advance major plot points. Compared to most first-person shooters of the time, which relied on cut-scene intermissions to detail their plotlines, Half-Life's story is told mostly using scripted sequences (bar one short cutscene), keeping the player in control of the first-person viewpoint. In line with this, the player rarely loses the ability to control the player character, who never speaks and is never actually seen in the game; the player sees "through his eyes" for the entire length of the game. Half-Life has no "levels"; it instead divides the game into chapters, whose titles flash on the screen as the player moves through the game. Progress through the world is continuous, except for short pauses for loading.
The game regularly integrates puzzles, such as navigating a maze of conveyor belts or using nearby boxes to build a small staircase to the next area the player must travel to. Some puzzles involve using the environment to kill an enemy, like turning a valve to spray hot steam at their enemies. There are few bosses in the conventional sense, where the player defeats a superior opponent by direct confrontation. Instead, such organisms occasionally define chapters, and the player is generally expected to use the terrain, rather than firepower, to kill the boss. Late in the game, the player receives a "long jump module" for the HEV suit, which allows the player to increase the horizontal distance and speed of jumps by crouching before jumping. The player must rely on this ability to navigate various platformer-style jumping puzzles in Xen toward the end of the game.
For the most part the player battles through the game alone, but is occasionally assisted by non-player characters; specifically security guards and scientists who help the player; the guards will fight alongside the player, and both guards and scientists can assist in reaching new areas and impart relevant plot information. An array of alien enemies populate the game, including headcrabs, bullsquids, and headcrab zombies. The player also faces human opponents, in particular, Hazardous Environment Combat Unit (HECU) Marines and black ops assassins.
Synopsis
Setting
Most of the game takes place in the Black Mesa Research Facility: a fictional scientific complex built in a remote desert region of New Mexico. The game's protagonist is theoretical physicist Gordon Freeman, who becomes one of the survivors of an experiment that goes wrong, when an unexpected "resonance cascade"—a fictitious phenomenon—rips dimensional seams, devastating the facility. Hostile aliens from the Xen dimension subsequently enter Black Mesa through these dimensional seams, attacking any human on sight.
With the cooperation of surviving scientists and security officers, Freeman tries to escape the ruined facility, but soon discovers that he is caught between two sides: the hostile aliens and the Hazardous Environment Combat Unit, a U.S. Marine Corps special operations unit dispatched to eliminate the aliens and any surviving Black Mesa personnel—both to cover up the incident, and destroy all contamination. Throughout the game, a mysterious figure known (but not actually referred to in-game) as the "G-Man" regularly appears and seems to be monitoring Freeman's progress. Ultimately, Freeman's goal shifts to reaching Black Mesa's mysterious "Lambda Complex" (signified with the Greek lambda character "λ"), where a team of survivors is rumored to have found a way to end the disaster once and for all.
Plot
Physicist Gordon Freeman arrives late for work at the Black Mesa Research Facility. He dons his Hazardous Environment (HEV) suit to carry out an experiment taking place in the Anomalous Materials section of the facility. When he pushes an unusual material into an anti-mass spectrometer for analysis, the spectrometer explodes, creating a "resonance cascade" that opens a portal to another dimension, Xen.
Gordon escapes the destroyed lab. Survivors tell him that communications with the outside world have been cut and urge him to head to the surface. Gordon fights his way through Black Mesa, defending himself against hostile Xen creatures (such as Vortigaunts and parasitic headcrabs), and U.S. Marines sent to cover up the incident.
On the surface, Gordon learns that scientists from the Lambda Complex may have found a way to close the portal. Gordon travels to the other end of the facility to assist them. Along the way, he activates a rocket engine test facility to destroy a giant tentacled creature and uses a disused railway system to reach and launch a satellite rocket. After he is captured by marines and left for dead in a garbage compactor, he escapes and makes his way to an older part of the facility, where he discovers Xen specimens collected before the resonance cascade.
