Half-Life: Opposing Force is the official game expansion for Half-Life, the thrilling PC CD-ROM named "Game of the Year" by over 50 publications. In Opposing Force (a.k.a. "Op For"), players return to the Black Mesa Research Facility to experience an entirely new episode of single player action. In addition, Op For also contains a massive collection of new multiplayer content.

Remember the soldiers who gave you so much trouble in Half-Life? Now you are one of them--and life is not so easy as part of the Opposing Force.

As a soldier sent in to eliminate Gordon Freeman, you are separated from your base unit and discover a new alien race amidst the chaos. It's quickly revealed that these highly advanced alien life forms descended upon Earth to pillage the planet from the Black Mesa facility when Gordon Freeman transported to the border world of Xen.

Although you were originally sent into Black Mesa to silence Freeman and his fellow scientists in the facility, you now find yourself stranded and confused--battling fierce new alien creatures and a variety of other foes in an effort to save your own life.

But as a military specialist, you are not unarmed. You'll gather a custom arsenal of new military firearms, experimental weapons and deadly alien devices. And, as you explore further areas of Black Mesa, you will encounter a new variety of human characters to interact with--on both friendly and unfriendly terms.

In addition to the extensive new single player experience, Opposing Force will also contain a robust collection of fresh multiplayer content, including new weapons, player characters (models), and several new multiplayer maps designed by the experts at Gearbox Software. Opposing Force will also feature new levels created by all-star legends of the Dallas gaming community.

Opposing Force is being developed by Gearbox Software and published by Sierra. This official game extension is due to arrive in retail stores everywhere this November.

• Return to the Black Mesa Research Facility as a soldier.
• Experiment with a host of new military, experimental and alien weapons.
• Battle a fierce new alien race and interact with more human characters.
• Compete in new multiplayer maps designed by industry all-stars.

Opposing Force Introduction provided by Sierra's Official Opposing Force.

In Opposing Force you'll meet (or kill) some new faces, along with the old ones for the original Half-Life.

	The Grunts This time around, the grunts are your colleagues. There will be at least four new types of grunts (and existing grunt models have been improved upon), and you will be able to command certain ones much like you were able to team up with security guards in the original game. You can also order fellow soldiers to do certain tasks, like cutting through doors or healing your wounds. You'll also be able to call in these guys as reinforcements.		The Grunts A security guard who probably is responsible for eating all of the donuts. Expect him to exchange some nifty dialogue with Barnies. Otis won't be alone. Other variations on the security guards and scientists will occupy the facilities which Adrian ventures through in Opposing Force.
	Radiation Suit Scientists Walter and his friends are back again, this time sporting some brand new duds. Like the scientists in the original Half-Life, these guys can help you out in a number of ways, including healing you up, unlocking doors, activating retinal scans, and providing convenient cover for incoming gunfire. They die really nicely!		Drill Sargeant This is the Drill Sargeant who'll guide you through the Boot Camp (Opposing Force's version of the Hazard Course). He's a rough and ready feller, and with the voice acting of the man behind Duke Nukem, you can be sure he'll be barking orders in true Full Metal Jacket style. Don't give him any flak and you should come out just fine.

	Zombie Grunt An unfortunate grunt who got himself headcrabbed and turned into a zombie. Expect headcrabbed security guards, as well. These creatures are, as you might expect, rather mindless, though don't underestimate them. They're quite dangerous enough, especially if they get close enough to start slashing at you with their claws. Very nasty stuff.		Pit Drone The Pit Drone is one of the new Race-X aliens, a race of aliens that appeared in Black Mesa after Gordon left for Xen. The Pit Drone is somewhat similar to the Alien Slave, and are controlled by mysterious and unseen entity. Pit Drones have the ability to shoot spikes from their forehead, which regenerate in time.
	Shock Troopers An incredibly intelligent breed of Race-X alien. They work in packs and communicate with each other, much like human grunts, and can open portals to bring in reinforcements.		Shock Roach A pint-size buddy to its trooper brethren, this little varmint spits electricity. Being a parasite, it's usually near one of the larger aliens, so watch your step in a fire-fight or he might pop his head up and zap you.
	Voltigore Big, bad-ass four-legged momma-jamba. 'Big' being somewhat of a feature on Voltigore, the frontal claws are just so, and deadly. It likes spitting electricity, too. And in true Geiger fashion, when it dies, it becomes unstable and explodes, causing you quite a bit of pain if you're in the near vicinity!

In Opposing Force you get the some of the old weapons for the original Half Life along with at least seven new weapons. You play as a Grunt on Opposing Force this time around, so you're going to have to access different types of hardware, and some better weapons.

	Wrench Say good-bye to your old crowbar, and say hello to this new more powerful Pipe Wrench. With the new pipe wrench you can use the secondary fire, and it'll be a more powerful swing, crushing almost crush any crate in one swing.		Barnacle Remember those things hanging down in Half-Life, where if you touched one you'd be sucked up to the ceiling? Well now it's a weapon, you can use it as a grappling hook, use it's tongue to suck enemies in, or you can use it to swing through the air.
	.357 Desert Eagle Just like the magnum from Half-Life, but it has a better design, and also has an alternate fire laser sight.		M-249 SAW Lets just say this is one hell of a gun, and it'll send out the bullets as fast as you can hold the trigger.
	Displacer Yes, its another one of those experiments, you can fire teleporters at your enemies, or teleport yourself to Xen.		Shock Rifle For all those Unreal Tournament people out there you probably know what this is.
	Spore Launcher This alien biological weapon is basically a biological grenade\rocket launcher. Fun with Spores -- there's nothing like it!

Here's a small collection of Screen Shots from Half-Life: Opposing Force.