Closer to the original HL than Opposing Force, which I personally like. It's not very memorable though, the encounter design definitely tries its best to mimic what Valve were going for.... sometimes that shines through, fighting the military in this is great, but the encounters don't have that same kind of "oompf" to them that they do as Freeman.

There isn't that encounter where you reach the surface and it's absolute hell on earth before you immediately get forced back inside. There's no Surface Tension. Instead there's a lot of.... creeping through the dank sublevels. It's another kind of atmosphere, it works in its own right, but it's kind of just a reminder of what this was going to be before it became what it is.