The Best game made by Valve.
Storyline: Not so good, everything you do is in first Person, no cut scenes, but that's what makes the game realistic, you can feel the person is actually talking to you. I'll give it a fair 6.0/10.
Graphics: All I can say is... AWESOME level of detail! If you own a low-end PC this game will still run pretty good, and this is a 2004 game? Looks more of a 2010 game me. We all know graphics don't make the game, but Half Life 2 probably has best game with good graphics. I'll give it a perfect 10.0/10.
Gameplay: Really good gameplay, even better than Halo, in Halo they show nothing but cutscenes. The gameplay get's a great 8.5/10 from me!
Controls: Just standard controls for an FPS, ASDW, Shift, R, F, and Z. 10.0/10
Weapons: They can get a little to repetitive, but the sounds match perfectly, I really did like the SMG sound. Weapons get a good 7.0/10.
Mods: There are over 100,000 mods for this game on Moddb.com, Black Mesa Source is still in making and I'm definitely gonna download it when it releases. Mods get a full 10.0/10.
A few bad things about the game: Well... I don't want to say it but I'll say it, the game is a bit slow paced, not mention steam. I don't really like steam, it messes up sometimes. If this game was standalone it would have gotten my full 10.0.
Overall I give this game a great 8.5/10.