This article describes the computer game. For the meanings in chemistry and other sciences, see half-life.

Half-Life is a first-person shooter computer game developed by Valve Software and published by Sierra On-Line in 1998, based on a heavily-modified Quake game engine. It was first published for PCs running Microsoft Windows, and was later ported to Sony's PlayStation 2 video game console. Half-Life, often shortened to HL, has been heralded by computer game critics for its gripping in-depth storyline, which would influence the development of other first-person shooters in the years to come.

Single player

The protagonist of the game is the scientist Gordon Freeman, a survivor (and catalyst) of an experiment that goes horribly awry, ripping dimensional seams that allow aliens from a dimension known as Xen to invade Earth. The game refers to this as a resonance cascade. As Freeman tries to escape the overrun facility he soon discovers he is caught between two sides: the hostile aliens, and the forces of the United States Marine Corps which has been dispatched to cover up the incident—including Freeman and the rest of the scientists. Throughout the game, a mysterious figure known as the G-Man regularly appears to monitor (and direct) Freeman's progress.

The setting for the game, the fictional Black Mesa Research Facility, bears many similarities to both the Los Alamos National Laboratory and Area 51.

The plot was written by Valve's in-house writer and author, Marc Laidlaw who wrote the books Dad's Nuke and The 37th Mandala.

Chapters

In this scene, the player must cross a dam; but the dam is guarded by an Apache helicopter, and the lake is inhabited. This shot also shows the original MP5 sub-machine gun, instead of the High Definition Pack's M4/M203 replacement.

The game storyline is divided into "chapters":

1. Anomalous Materials - Gordon is running late for an important experiment. After donning his HEV suit, he makes his way to the test chamber to assist with the experiment, but something goes terribly wrong.
2. Unforeseen Consequences - Disaster strikes: A resonance cascade has been triggered, causing massive structural damage to Black Mesa. Worse yet, Xen aliens begin teleporting in all over the place, attacking the few survivors who are left to fend for themselves.
3. Office Complex - Gordon works his way to the surface and hopes to get help from newly arrived marines.
4. "We've Got Hostiles" - The marines take command of Black Mesa and are killing everything, human and alien alike. Gordon learns that members of the science team have retreated to the Lambda Complex at the other end of the facility and can help him.
5. Blast Pit - Gordon runs into a sort of giant animate alien plant that has nested in a rocket testing area. By firing the rocket engine suspended above the creature, he destroys it and is able to follow the tunnel it leaves behind to the old rail system that leads to Lambda Complex.
6. Power Up - Gordon reactivates the rail system's power, fights off the hostile marines, defeats a large alien, and takes the train to Lambda.
7. On a Rail - A guard informs Gordon that a communications satellite needs to be launched to activate equipment at the Lambda complex. Gordon fights his way through the rail system, finding entrenched Marines lying in wait for him, and launches the satellite's rocket.
8. Apprehension - Gordon runs into some mysterious assassins and later the Marines finally apprehend him and dump him in a garbage compactor.
9. Residue Processing - Gordon makes his way through "residue processing", a dangerous, ancient area of the complex filled with hazardous materials and automated materials processing equipment.
10. Questionable Ethics - With the help of hiding scientists, Gordon makes his way through laboratories designed to perform experiments on alien lifeforms. Apparently they were on Earth long before the resonance cascade. Eventually he reaches the surface and tries to meet up with the remaining scientists at the Lambda Complex.
11. Surface Tension - The surface is swarming with aliens and marines, who are losing their fight. Gordon learns that the marines are planning to pull out and start air strikes on Black Mesa.
12. Forget About Freeman - The marines are ordered to evacuate immediately and Gordon finally arrives at the Lambda Complex.
13. Lambda Core - Gordon activates the reactor for Lambda and learns of the secret teleportation experiments that have allowed expeditions to the alien "borderworld" of Xen. An immensely powerful being in that borderworld is keeping the portal between the worlds open. Gordon enters the teleporter.
14. Xen - Now on the strange borderworld, Gordon encounters many of the aliens that had been brought into Black Mesa, as well as the remains of HEV-wearing researchers that came before him. He activates an alien teleporter and is whisked away.
15. Gonarch's Lair - Gordon faces a powerful spider-like creature - literally the mother of all headcrabs - in its own lair. After defeating it, he finds a portal and enters it.
16. Interloper - Gordon arrives at an alien factory. After sneaking and fighting his way through, he finds another portal and enters it.
17. Nihilanth - At last, Gordon confronts the powerful being that is holding the portal open: Nihilanth. Gordon defeats the creature by destroying its brain and is met by the mysterious G-Man who offers Gordon an ultimatum: either work for the G-Man or be abandoned on the alien world, where he would have no chance of surviving.

Multiplayer

Years after its release, Half-Life (and in particular, its numerous modifications) continues to be popular even now that most players have completed the single-player mode. Playing over local area networks and the Internet, players can fight against each other, or cooperatively, just as in previous first-person shooters.

Online play for Half-Life was originally through WON but is now through the Steam content delivery system. Users can download and play any version of Half-Life and any available mod, or even purchase the game online, through Steam. Valve introduced Steam to Half-Life in 2003, 5 years after the game's November 1998 release date. Steam now serves as the basis for online play for many games, notably Half-Life 2.

Despite being somewhat eclipsed by its many successful multiplayer mods, Half-Life Deathmatch (HLDM) is still popular and is played in various leagues around the world.

Sequels, expansions and mods

From its release in November 1998, Half-Life saw fervent support from independent game developers, due in no small part to support and encouragement from Valve Software. Worldcraft, the level-design tool used during the game's development, was included with the game software. Printed materials accompanying the game indicated Worldcraft's eventual release as a retail product, but these plans never materialised. Valve also released a Software Development Kit, enabling developers to modify the game and create mods. Both tools were significantly updated with the release of the 1.1.0.0 patch. Many supporting tools (including texture editors, model editors, and rival level editors) were either created or updated to work with Half-Life.

Ports

Half-Life was ported to the PlayStation 2 by Gearbox Software and released in 2001. This version of the game added Head-to-Head play and a co-op expansion called Decay that allowed players to play as two female scientists at Black Mesa.

Versions for Sega's Dreamcast and Apple Macintosh were completed, but never released commercially.

Expansions

Two expansion packs by outside developer Gearbox Software have been released: Opposing Force (1999) and Blue Shift (2001). The former, often shortened to OpFor, returns the player to Black Mesa during the events of Half-Life's storyline, but this time from the perspective of the U.S. Marines sent to cover up evidence of the incident. It introduced several new weapons (notably the M249 SAW LMG and a Barnacle grappling gun), new NPCs, both friendly and hostile (Otis the security guard and the "Race X" aliens, respectively) and new, previously unseen areas of the facility. The game is shorter than Half-Life, having 11 chapters to the original's 17.

Blue Shift returns the player to HL's Black Mesa timeline once more, this time as one of the facility's security guards. (This expansion was originally developed as a bonus mission for the canceled Dreamcast version.) Blue Shift came with an optional High Definition Pack that could update the look of Half-Life, Opposing Force, and the new Blue Shift content. In particular, the models' polygon count and texture resolutions were increased, and some changes were made to the in-game sounds, most notably the shotgun. Blue Shift had relatively little new content compared to Oppposing Force: aside from a few models (jacket-less scientists and security guards, Otis, and Dr. Rosenberg) all content was already present in the original Half-Life.

Half-Life: Decay was another expansion by Gearbox, released only as an extra with the PlayStation version of Half-Life.

Mods

Half-Life's code has also been used as a base for many mods such as the immensely popular and free multiplayer mod, Counter-Strike. Other popular multiplayer mods include Team Fortress Classic (TFC), The Specialists, Day of Defeat, Deathmatch Classic (DMC), Action Half-Life, Firearms, and Natural Selection. TFC and DMC were developed in-house at Valve Software. Counter-Strike, The Specialists, Day of Defeat, and others began life as the work of independent developers (self-termed "modders"), later on received aid from Valve. Numerous single player mods have also been created, such as Half-Life: Absolute Redemption (http://www.maverickdev.com/redemption/redemption.htm) by the UK based Maverick Developments (produced as a free PC addon pack for Valve in November 2000, bringing back Gordon Freeman for 4 additional episodes and another encounter with G-Man).

Some Half-Life modifications eventually landed on retail shelves. Counter-Strike was the most prolific, having been released in three different boxes: as a standalone product, as part of the Platinum Edition, and as the single player spin-off, Condition Zero.

Half-Life 2 and Source

The sequel, Half-Life 2, was merely a rumor until a strong impression at E3 in May 2003 launched it into levels of hype only equalled by Doom 3. The player again takes the role of Gordon Freeman, this time many years after the Black Mesa incident in a dystopic Eastern European 'City 17' where he must fight as part of a rebellion against an alien takeover. After a series of controversies and delays Half-Life 2 was released on November 16, 2004.

Valve ported Half-Life to their new Source engine, which has been dubbed Half-Life: Source. Valve ported HL (and later Counter-Strike) to experience first-hand the processes mod-makers would have to go through. Half-Life: Source is a straight port, lacking new content or the Blue Shift HD pack, which is available with special editions of Half-Life 2.

Weapons

There are 14 weapons available to players in both single-player and multiplayer games of Half-Life. Half-Life: Opposing Force added several more weapons. The weapons in HL (without expansions) are:

• Crowbar: A simple melee weapon that is iconic of Freeman and Half-Life.
• Pistol (GLOCK 17, Beretta M9 pistol with the High Definition pack): The first and simplest ranged weapon. Has good accuracy but low damage that makes it more useful on weak targets, like headcrabs or laser trip mines. Unlike most other ranged weapons, this pistol is effective underwater. Primary fire is accurate with every shot; secondary fire is faster but less accurate.
• Magnum (Colt Python revolver): An extremely powerful and accurate gun. It has a long reload time and a small 6-round clip. Good for dispatching enemies in one hit, especially from a distance. In multiplayer mode, secondary fire gives the player a zoomed view.
• Submachine gun (HK MP5/A3, Colt M4/M203 assault rifle with the High Definition pack): Excellent for close-range combat. Has a fast rate of fire that compensates for its poor damage and accuracy. Secondary fire launches a grenade that detonates on impact.
• Shotgun (SPAS-12): Does high damage at close range, but its broad fire cone makes it weak at a distance. It can be reloaded one shell at a time, but is slow to fully reload. Its secondary fire shoots two rounds at once.
• Crossbow: A sniper weapon with high damage and accuracy, but with a slow rate of fire and reload time. Like the pistol, the crossbow works underwater. Secondary fire toggles its zoom mode. Multiplayer behavior is quite different: It fires explosive bolts, and when zoomed in it's an instantaneous-fire sniper weapon.
• Hornet gun (alien weapon): The same weapon used by the Alien Grunts, this gun is a sort of living hive of constantly replenishing "hornets". Primary fire shoots up to 8 homing hornets that can hit unseen enemies around corners. Secondary fire launches straight-flying non-homing hornets that move faster and have a higher rate of fire compared to the homing ones.
• RPG launcher: Does a large amount of explosive splash damage. Secondary fire toggles a laser that guides the RPG to its target. Can only hold one rocket at a time with 10 more in reserve.
• Gluon gun: This experimental weapon looks and operates similar to the proton pack used by the characters in the movie Ghostbusters. Because of its internal weapon name, weapon_egon, it is also known as the Egon gun; this is probably a reference to the identically-named character from the movie. This gun emits a powerful, continuous, bluish energy stream.
• Tau cannon/Gauss gun: Another experimental weapon that rapidly shoots laser-like beams that reflect off walls if hit indirectly. Secondary fire allows the gun to charge up to shoot a more powerful beam that can penetrate thin walls and pushes the user in the opposite direction. The recoil is deliberately exaggerated in multiplayer so the player can "Gauss jump" very high and reach hidden areas or escape opponents. This feature is a deliberate nod to "rocket jumping" in Quake. If the gun is kept charged for too long, it overloads and damages its wielder.
• Hand grenade: A frag grenade that explodes a few seconds after being thrown.
• Laser trip mine: A high-explosive Claymore-like mine that can be attached to walls. It is set off either by damaging the mine or by "breaking" the laser "tripwire" emitting from it.
• Satchel charge: A high-explosive that can be thrown a short distance and detonated when the player presses fire. The player can place several satchels and detonate them simultaneously.
• Snarks (alien weapon): Aggressive little alien creatures that quickly pursue their target, pestering and biting, until finally expoding after several seconds. If they cannot locate a hostile target, they will turn on the player that set them loose. Can be used, for example, to draw enemies out from their cover.

See also

• AMX Half-Life Server Mod
• List of Half-Life mods

External links

• The Official Half-Life Web Site (Sierra) (http://half-life.sierra.com/)
• Planet Half-Life (GameSpy) (http://www.planethalflife.com/)
• The Half-Life Saga Story Guide (http://hlstory.fragfiles.org/)
• Valve ERC Collective (http://collective.valve-erc.com/)
• Pro HL (http://www.pro-hl.com)
• Half-Life Clan Collision League (http://www.hlccl.com)
• Half-Life Gameplay Videos (http://nato.daddeln.de/pv/index.php?nav=files&action=show&id=18)