Half-Life

The Black Mesa Research Facility is an ultra-secret laboratory under a government contract to conduct top-secret and extremely volatile experiments. The scientist Gordon Freeman is a Black Mesa employee. One morning, as usual, he pits his way to the research facility for a run-of-the-mill experiment. However, Gordon comes to realize that it might not be as ordinary as he thought. Odd things happen as he makes his way to one of the Black Mesa test chambers. Even stranger things happen when he begins to move the test sample towards the anti-mass spectrometer.

At that moment, everything goes horribly wrong. Aliens from the dimension Xen suddenly invade the facility, injuring or killing many of the employees. Soon afterwards, marines arrive to contain the situation by killing the aliens as well as the surviving human witnesses. Gordon understands what that means: he will have to fight his way through both aliens and marines to get to the top of the Black Mesa complex and to freedom.

The story of Half-Life is told entirely in-game: everything is seen through the eyes of the protagonist. Most story elements unfold via scripted sequences, triggered by the player reaching a certain area. If other characters have information to reveal, they address Gordon directly. The Black Mesa complex in the game is made up of both distinct levels which progress in a linear fashion as well as hubs where backtracking may be required to unlock further areas.

The game's weapon arsenal mostly consists of realistic weapons like pistols, machine guns and explosives, but there are also futuristic energy weapons developed at Black Mesa as well as organic weapons acquired from the invading aliens. Most weapons feature an alternate firing mode.

Enemies fall into two categories: aliens and human soldiers. While most of the aliens are not very bright, the humans display some relatively advanced artificial intelligence: they seek cover, retreat when hit and try to drive the player from his cover by throwing grenades. Some of the alien enemies cannot be killed by normal means. The environment must be used against them instead, going with a general tendency of the game to alternate the combat with environmental puzzles.

As of the 25th Anniversary Update from 17 November 2023, the Steam version of Half-Life includes content from Half-Life: Uplink as well as sprays and maps from Half-Life: Further Data V.1.