Just like Blue Shift, Opposing Forces is a great expansion to Half Life 1. There's a lot more in this, but I found it to be not as good as Blue Shift in terms of pacing. I found that the squad members you can bring along SUCK at path finding. They would often get stuck or stop following you and I found it extremely annoying. I did like the new variety of weapons that it brings. That was really good. I can see why everyone likes it the most, but I feel that the changed arsenal and the increased playtime more than makes up for the issues I have with it. Overall a great time still, and I very much recommend it, of course that is if you've played Half-Life 1.