When I first played Half-Life 2 I couldn't fathom how different it was to Half-Life 1. From the labs of Black Mesa to Ravenholm? You would have thought they were completely and utterly unrelated games.
Also, the interactivity in Half-Life 2 seemed to be greatly reduced from that of Half-Life 1. As an example of this, the people who you come across don't seem to be reliable like they were on Half-Life 1. A Barney would constantly shoot any head crabs whereas the rebels of Half-Life 2 seem to run around a lot and do less shooting.
The graphics of Half-Life 2 have a much less "solid" feel if you know what I mean. On Half-Life 1 with the high definition pack on everything was nice and chunky and detailed in their texture, whereas on H-Life 2 things are still detailed, but you can step through things like bodies. On Half-Life 1 you would feel when you walked over something. The variety of enemies is also a lot less.
The weapons also don't feel as nice. When you used the Magnum on Half-Life 1 it would feel all chunky and powerful. But on Half-Life 2 it just feels like a picture which an animation and a sound playing when you shoot it. And Gordon doesn't fiddle with the weapons anymore either. Infact, he doesn't even move them around. They just stay there, static, unless the player moves.
I have just been looking at the Half-Life nostalgia project, that is what triggered all this
http://nostalgia.planethalflife.gamespy.com/halflife/cuttings/im_spring98b.jpg







