The gameplay isn't signficantly different from Half-Life at all. Opposing Force contains that perfect blend of action and puzzles that made Half-Life so interesting. While not nearly as spooky as System Shock 2, or as pulse pounding as Aliens vs. Predator, some people would argue that Half-Life can be kinda scary. As for me, I wouldn't play Half-Life or Opposing Force to get scared, if that's what you're looking for. Before you start the game, you can go to 'Boot Camp', which is much like Half-Life's 'Hazard Course'. I recommend you do so too, because Opposing Force introduces us to ropes, which you sometimes have to swing around on to get to places. Nightvision, which has an interesting, and creepy look to it, has replaced your flashlight...and like any good add-on, you'll be treated to a bunch of new weapons, enemies, and even allies.

The level design is superb. Again, the game takes place in the Black Mesa, during the events of Half-Life, meaning the levels don't differ much in terms of looks. You'll travel through the usual scienve labs, the desert, underground tunnels, storage areas, and even the mysterious Xen, for a short period of time. Xen seemed to be the least favorite part of Half-Life, according to fans, so Gearbox did it's thing and did away with it. I hope you like crawling too, because there's alot of airshafts to crawl through. ;) The illusion that the game is one big level is still there as well. In Half-Life, when you entered a new level, it seemed like you had merely stepped into another area, when in fact, all the levels were chained together...an interesting technique. There are times when the level design really shines. One of the most memorable events was having to take cover behind bombed out buildings and a damaged tank, while dodging an enemy soldier raining mortars at you from the other side of the field.

You'll encounter the new enemies more often than the old ones. For starters, there's the Shock Trooper- a 4 armed creature, with one big reptilian eye that fires electric shots, and lobs grenade-like explosives at you. Once killed, their weapon comes alive and comes after you much like a Head Crab. Shocktroopers are a sort of substitute for marines, who you don't fight anymore (unless you attack them first!). Unfortunately, they're a hell of alot tougher than your marine buddies. You'll also be facing drones, who are dangerous, especially when hunting in packs, as well as huge Voltigores. In addition to those, a few bosses make up your alien enemy list. The headcrab zombie also has a beefed up version...Not only are they faster, but they can hurl peices of themselves at you. Possible Spoiler : You'll find out those 'Black Ops' dislike you about as much as Mr.Freeman. The Black Ops were the fast, stealthy ninja-like soldiers in the original Half-Life. The female versions are incredibly tough, but fortunately, you'll run into the male ones more.

In addition to Half-Life's weapons, you'll have two new groups, for a total of seven. The 6th group contains high end military weapons, such as the powerful SAW Light Machine Gun, Sniper Rifle, and Displacer Gun, which can eliminate almost any enemy in one hit by teleporting them to another dimension, never to be seen again. Group 7 contains two alien weapons, which are nothing special [imo]. Certain weapons, you won't have access to. Instead of getting a Crowbar, you get the 'Big Red Wrench', and a Knife. Instead of getting a Magnum, you get the Desert Eagle. You'll also get the Barnacle Gun, which when shot, attatches itself to something, and pulls you towards it...or it towards you, if it's small enough.

During your trip around the Black Mesa, you'll encounter quite a few marines from your platoon, who you can order to follow you around. First off, there's your basic offensive soldier, the grunt. Then there's medics, who of course heal you and others with their limited supply of health. If need be, they'll fall back to their pistol. And Engineers, who carry the 'Big Red Wrench' and can open up locked doors. Other than soldiers, there's a new type of security guard you'll see only once in awhile named 'Otis'. These are fat, and rather clumsy versions of the 'Barney' security guards. I actually got killed by one, who was shooting at an already dead alien...

Opposing Force is a very good game, but I do have a few things to bitch about. One complaint I have is about the AI which gets so good comments. It's great for the enemies, who team up on you and take cover, but more often than not, I'm left wanting to punch out my allies due to their stupidity. In one case, I ordered one of my grunts to cover myself and another soldier while we scouted ahead. We were ambushed, so we ran back, and the other soldier ran RIGHT into the gun of the grunt who stayed behind, killing him...even worse was the grunt was firing at an alien I had just killed. Friendly AI units continue to fire at aliens who have just died for a few seconds after they've stopped moving...which cost me health a few times. They'll also get stuck around door ways, and sometimes not follow you even if they've acknowledged that they'd do so. This is especially annoying when you try to make them follow you into new maps. Every once in awhile though, something will happen, like a grunt will through a grenade, and warn everyone while ducking and running for cover and your other soldiers will do the same. It's neat, but the AI is hardly anything close to perfect...

Another complaint of mine is the shortness of the game. I like to think of myself as a 'seasoned FPS veteran', but this game took me 3 (days of school) to finish. For the original price of $39.95, I would have definately felt cheated by the game's shortness...but thankfully I paid $9.95 at Best Buy's. I admit I haven't tried the multiplayer portion of the game, but several maps by high profile map makers, like 'Levelord', 'Paradox', and 'Kevlar' are included. The old deathmatch maps have also been updated with Opposing Force's new weapons. I'm sure anyone who's been interested in doing so has bought Opposing Force already...But if you can get it in the bargain bin for $9.95, I suggest you do so. It's a short and sweet add-on that will keep you busy for a few hours.