Originally Posted by M.C
It's Half-Life with better graphics, animations, and new voice acting for the characters. The game is 100% the same otherwise.
There are actually some pretty big differences. Characters cut, weapon functions altered, no hazard course, changes to levels. The basic plot and map progression will stay the same, but this isnt just a port from the old engine with some replaced AV assets, this is a recreation from the ground up.