The game was just. . . awesome. It definitely gets my vote for game of the year. The environments were alive. The level design was flawless. The story was immersive. The graphics were cinematic. The use of music was perfectly timed. And the gravity gun, I mean, come on, it has to be the most creative weapon/utility tool ever created for a game. It is so satisfying to mow down 5 zombies with one sawblade.
I think that Half-Life 2 has shown all other games what they could be. I hope other developers can raise their games to the level of HL 2, but for now, it is head and shoulders better than the rest.