Repeating Dream

I stand alongside a group of people I do not know in real life, but in my dream I know them. There is something urgent me must do and we are all armed in some way. We are in a building, waiting on a darkened ramp on the inside preparing to charge up and around the corner into a lit room where our objective was. We finally moved and we ran up the ramp and into the sunlight room. The room was large and had the base of a tower off to the left of the ramp, towards the center and all around it, save for the concrete platform we were on, was deep septic water that looked a deep green. From this water crawled out a type of creature from a game I enjoy. They are from the game series Half-Life and they are humans who have head creatures called Headcrabs take control of their minds. These forcibly controlled zombies marched out of the much and suddenly I was all alone with the creatures in the way of the path of floating debris that I needed to get over to get inside of this tower. With the gun I had I ran through the creatures, disposing of those only directly in my was before quickly moving into the tower. From here, I', unarmed and I feel as though I'm being chased. I'm inside and each room is a puzzle to get me higher into the tower and further away from my pursuers. I cant see them and I don't even know what they are but I can feel them catching up. I have to solve a puzzle for each floor, they just have to follow my answer. This goes on for a few floors before I feel as if they could be right behind me and that's when I wake up, panting as if I had been actually trying to run from something.