The game that started what people call the modern story based FPS. I have to say, as somebody who doesn't play FPSes all that often. This was an alright game. Sure it suffers some flaws but they can be overlooked. Easily overlooked if you take the game as a whole.
I love how the game starts. It's just a typical day for the silent protagonist, Gordon Freeman, and you get to be him. Sure, things go sour pretty fast but everything you need to know is introduced shortly thereafter and the game gets going. What sets this apart from other FPS games is that you are trying to survive and escape at the same time. You objective isn't always clear at times but the main goal is to survive what has happened.
This leads me to the first issue I have with the game. A lot of times I ended up wandering around for a while because I didn't know where to go or what I could interact with. At one point, I ended up doing a whole section of the game without an integral piece of the stage with me and had no idea I was even supposed to use it. Did I make it without it? Sure, but it was rough.
Secondly, the bosses in this game (particularly the last one) often make no sense and don't give you any clues how to hurt them unless you are paying attention. I died a lot of times before I figured out what I was supposed to be doing on the last boss. It probably is my lack of skill for this game that caused this but I found it a particularly negative point in the game. I didn't want the game to hold my hand but at some point I have to figure out what to do and I just couldn't.
This is a classic and should go with any collection. Even if you don't like the genre, this game is more than worth a play or two. Even the expansions add more to the story and you know what is going on at the end of it all. Play this game now, you have no reason not to.