In this video, things start heating up inside the Black Mesa compound as the scientists and freeman have to deal with a lot more than simple creatures. Starting in the freezer, you'll find the solution to the freezer puzzle.
I then have to deal with auto turrets galore, set off of course by trip lasers. It isn't too long before Gordon Freeman becomes quite familiar with the unpleasant military aspects of Black Mesa, as tripmines then rear their ugly head.
As an elevator comes down a scientist comes to a horrible realizion - the soldiers aren't here to help us. But they want to eliminate the evidence of what's going on in the Black Mesa compound.
Towards the end of the video you will see me grab the machine gun and start taking on the enemy soldiers. Just like in the original Half-Life 1, Black Mesa Source's soldiers have excellent AI as I start playing a game of cat and mouse to see how they respond to various actions.