Most people probably won't play much if anything of Blue Shift, so here's what you need to know for future installments if you skip this one: You play as Barney and nothing he does in this game is ever brought up later in the series. Yeah, Barney is sort of a main character in Half-Life 2, but this game manages to not get mentioned once throughout that one. Kind of weird, huh?
The thing about Blue Shift is that it actually isn't a bad game-far from it, actually, but when compared to the other games in the Half-Life 1 "series" it's just sort of there. Opposing Force introduced new weapons, music, characters and a lot to keep it fresh, while Blue Shift doesn't add a single thing and just rides on the coat tails of the fame that came from games before it.
So how is Blue Shift (which I just realized has the acronym BS, teehee) not terrible, since I'm bashing it so? Well, it sticks to the core Half-Life gameplay as I said, and you really can't go wrong with it. It's fast paced, balanced, well designed, and is very atmospheric if you allow yourself to be immersed into it. But despite all this, if you've played the games before it, than Blue Shift is just... boring. I don't want to be too rude, because I really do think this is a good game, but there just isn't enough new stuff in Blue Shift to keep it interesting,
It reuses Opposing Force's soundtrack, gives you only three fourths of the first game's weapons, and the story is...oh, right! That's a good part! G-Man (a staple of the series) only appears once, in the beginning of the game. He's even absent from the ending. This may sound lame, but it's sort of assumed by now that G-man would be really prominent, so having him just show up once is a surprising and welcome twist. And when you think about it, it even makes sense! Why WOULD G-Man bother following some random security guard? It's actually kind of genius in a way. Oh yeah also the way they explain teleportation is absolutely brilliant and makes a lot of sense (no I'm not being sarcastic) and this is seriously the best explanation of teleportation I've seen in my life.
So, in conclusion, Blue Shift is.. okay. It doesn't pack the punch of the other games in the Half-Life Series (let's just pretend Decay doesn't exist,) and really doesn't have a purpose since it has no bearing on the story, but it's okay and can be occasionally genius when it comes to the story. It's too much of a rehash for me to really love it, but it certainly won't upset any Half-Life purists.