Half-Life x 2 = a Whole Life?
The game play is fantastic. FPS action with some cool puzzles. Weapons are sweet especially the gravity gun. It enables you to pick up so many things and throw it at the "bad guy". This is so much more enjoyable with the jaw dropping physics. The way you can kill an enemy is like doing a math problem. If you put a grenade under a dumpster it will be knocked over a platform which will fall on an enemy, or you can shoot them, or chop them in half with stuff you pick up with the gravity gun.
The graphics are the best out there. Environments are beautiful and so... well big. Great effects and awesome maps. The sound is another brilliant aspect and the voice acting is supurb. The guns sound like what a gun should sound like.
If you haven't finished it, finish it. If you finish it, play it again. If you dont have it, buy it.