Opposing Forces (OF) everything HalfLife was and a little bit more. The fact that OF managed to create a much more cooperative experience added to the gameplay quite a lot. In OF, you are one of the soldiers sent to kill Freeman from HalfLife, but when you get there your Osprey crashes and you end up fighting for your life against aliens and secret Black Ops forces.

Throughout the game, you come across other soldiers that can help you out - medics, engineers and other soldiers. By using strategically-placed radios, you can call for help and backup when you're most likely to need it. The best parts of OF are the mass battles between soldiers and aliens (or between soldiers and soldiers) where you feel you're right in the middle of a war zone.

Artificial Intelligence

Here is an extract from the Generation5 interview with Patrick Deupree, the man behind the Opposing Forces AI:

.: Interview with Patrick Deupree :. G5: What sort AI of techniques were utilized in Opposing Forces? A lot of the AI techniques used were those already present in the Half-Life engine. The existing path finding, sound detection, and visual detection code present made our job a lot easier. Some tweaks were done to this logic to accomodate new weapons. For example, the sniper rifle allows for an instant kill without any noise from the kill, so a special case had to be added for enemies near them to realize something had dropped dead next to them. However, rather than have them instantly know where you sniped them from, they will go into a "hunting" mode. We also used some techniques to "cheat" a bit. For instance, if you have a companion following you and you get shot, that companion will acquire the attacker as a potential target and they will try to rush in to defend you. Some people commented on the fact that our companion soldiers would often run into a situation and get themselves killed, but for what we were trying to accomplish, it was the better solution. G5: Were you ever surprised at what your AI achieved? We have a test map that I still use to this day to test AI that is called test_grunt. It was something one of the other developers here made, and I continue to modify. It's a lot of fun to make a change to the AI, or to add a new feature, and then hop into this map with some AI companions. Seeing how a team of human grunts would do when fighting a team of ShockTroopers would result in a different outcome just about every time. I think the coolest thing I saw was in one of our maps where you could have 2 grunts, a medic, and a guy with a blow torch but no weapon. I had the torch guy follow me into a hall containing a bunch of Black Ops and Ninja's and the torch guy took off down the hallway. I'd forgotten about him until I rounded the corner and saw him kicking the heck out of one of the ninja's until she was dead. I certainly hadn't expected it, though I had specifically put in code to make the grunts more inclined to use a melee attack in certain circumstances. .: Full Interview :.

Overall, this is definitely some of the most demanding AI in a first person shooter - the enemies all know their strengths and weaknesses and will fight accordingly (the aliens are relatively dumb, but soldiers can be smart as hell). Then again, any AI built on top of the HalfLife AI will yield very impressive results.

Gameplay

The scripted events in Opposing Forces were also nicely done, from the excellent introduction sequence, right through the game. In one such sequence a zombie (apparently under medical testing) suddenly gets up off the table, walks over to the scientist in the room, picks him up and throws him through the window! Great stuff.

All the new enemies were nicely done, and gave you more of a challenge than the original HalfLife - ShockTroopers were especially fun. The only problem I had with the gameplay came right at the end with the boss - it took me a long time to figure out how to kill the boss, in fact close to 70 minutes of play time. The final boss did seem fairly unbalanced - one I had figured out how to kill him, I could do it very easily.

There was an excellent new feature of Opposing Forces that I think the team took a little too far though - the night vision goggles. You can see the night-vision effect below, but you can't really appreciate it until you see it in motion. The system adds a sort of grainy effect like real NV systems. The screenshot at the right shows a view with and without the NV system engaged.

I think that the designers really liked this because a huge amount of the game is incredibly dark. A lot of major battles are done in areas that are nearly pitch black, and even more walking around in low-lit or dark areas. I really appreciated outdoors areas since it gave my eyes a rest from the green tint! It was an excellent feature, though, and did make some of the fighting sequences a lot more tense since you could only see about 6 feet in front of you.

Conclusion

	9.0
	Platform: PC Liked: Graphics, new cooperative AI, map design, sniper rifle! Disliked: Still fairly easy, very dark, the final boss was a little boring. .: Buy at Amazon.com :. .: Buy at Amazon.co.uk :.