This game was released in 2000 by Sierra Studios
and Rewolf Inc
. It is a first-person shooter
utilizing the Half-Life
engine, which in turn is based on the Quake
The game started its life as a mod for Half-Life. During Half-Life's initial exponential growth, which saw the birth of such other mods as Counter-Strike and Team Fortress Classic, and Half-Life's first expansion pack Half-Life: Opposing Force, Sierra pounced on this mod. Its creator, whose handle was Rewolf, essentially started his own company and was assisted in polishing up his amateure (though very well-done) game.
The game itself inherits more from Half-Life than just an engine. A number of the enemies share a passing resemblance to enemies in Half-Life, and many of the weapons can be traced to Half-Life's weapons. This isn't to say there aren't original monsters and weapons; this game also has its fair share of new things. Beyond all that, however, is a basic similarity to Half-Life's methods of presenting both action and story.
Half-Life was praised after its release for practically every aspect of the game. The AI was smarter (or at least more complex) than any other seen yet, and its level-transitioning system was unprecedented. It also featured an identifiable plot, with characters and things (which was very different from the Doom and Quake games).
Gunman simply used all of this over again. Half-Life's initial tram sequence, also a much praised method of presenting the story and setting, was used again. Gunman's was much more complicated, taking place in a zero-G space station, with the tram rotating at odd angles to the station. Knowing a bit about mapping for the Half-Life engine makes watching this all the more impressive.
The actual plot of the game follows a sort of interstellar Sheriff (a Gunman) trying to stop an ex-Gunman from doing something evil and destroying the universe. The game presents itself as a western in space ("It's High Noon in Deep Space").
The one thing this game does have that's new and unique is its weapon system. The game features several weapons that can be configured in a variety of ways. The basic pistol can be a simple pistol, a rapid-fire weapon, a weapon you have to charge up before every shot, or a sniper rifle. The rocket launcher has several things (the way you fire it, how it detonates, how it explodes) that can be changed in various ways (it can be a rocket that hits a surface and turns into a trip mine, or a heat-seeking missile, or several other things). There's another weapon that shoots a mixture of chemicals, and lets you alter the balance of acidic, basic, and neutral chemicals to varying effects.
Though the game uses a basically un-altered version of the Half-Life engine, it does not support mods, either for Half-Life or for itself. This functionality was intentionally removed, I presume so people would still have to buy Half-Life (and not the cheaper Gunman) to participate in its growing mod community.