Great game, the Enemy AI is second to none, the troopers being especially good. It has a really good 'oh God! what the hell is happening, i'm just a lone scientist, why did this have to happen to me?' feel. Also, it has possibly the greatest multiplayer in a game ever. And it has counterstrike.
Hmm... I really wasn't trying very hard when I wrote that...
Anyway: This is the big daddy-o of FPS shooters, having a comparable influence on the genre as other such timeless classics like Doom, and Wolfenstein 3D.
What Half-Life brought to the mix was a truly excellent storyline. Whereas before we had passable (Marathon) or laughable (Doom) storylines, Half-Life really promoted character development, plot twists, and other factors you'd expect more from a movie than a game.
The graphics, when compared to modern shooters are, obviously, now very lacking, but at the time when the game was first out, and for about a year and a half afterwards, were the shiznit. You can now get a 'high-definition' pack that brings the game more in line with newer games, but even with this, the game still lags behind. They are more than good enough to do the job, however.
Sounds are excellent throughout. The background noises are good at keeping the game's eerie feel intact, whilst weapon sounds, enemy interaction, footsteps, and all other foreground noise is better still. The music in the game, when it is even evident is not memorable in a Deus Ex kind of way, but it is moody and atmospheric enough.
I've already mostly commented on gameplay throughout this review, but there really are no words that can describe how flawless the gameplay in this game truly is, without actually playing it.
If we want to talk about longevity, then the fact that the game is still played to death, 5 years after it first hit the shelves should be evidence enough, but in slightly more detail, the single-player is very large, and difficult, so it'll take you a long time to complete. Once you have, then multiplayer will still have never-ending appeal.
Half-Life is:
the best FPS ever (probably)
rather dated
well worth your 5 bucks.
Half-Life is not:
overrated
past it.
Summary: I'd be surprised if there's many gamers who are yet to play this game, but for those of you who haven't; do.
Graphics: 8 (Good for the time, but missing definition nowadays)
Sound: 10 (Perfect)
Gameplay: 10 (Perfect)
Longevity: 10 (You guessed it; perfect)