I think people should care about half-life 2 because of the way it is designed. It may be linear and all 'plotty', but that's better than a one-page plot in a readme file or jewel case jacket.

Also, half-life 2 has a very impressive character animation engine this time out, with muscles and eyeballs for all characters. They even worked it out so emotions on the character faces look real with some rather slick logic and heavy research.

The AI for the aliens is a lot stronger now, and they now get distracted by easier targets and they also find their way around things better. Also, their feet actually touch the ground on rough terrain, and it affects their center of balance and everything. Very cool stuff. HURRR PHYSICS.