There is a full 'hands-on' review of HL2 in the June edition of PC Zone Magazine (I'm a subscriber) where the journalist spent a whole day with the developers and got to play the code, most of which is already finished. Here is a quote from the last paragraph in that review ...
"... Words failed me. My body felt exhausted as I relaxed my taught muscles,drained from the tension of watching a game which is re-writing the rule book and making a mockery out of every other first-person shooter I've ever seen. If you don't believe me, buy a ticket to E3, and find out for yourself. One things for sure though, come September, the world of gaming will change forever, and just like four years ago, its Valve that is showing us the way. With 40 hours of gameplay promised, its going to be one hell of a ride. All of a sudden, September seems like a very, very long way away ..."
The review is a full 12 pages long and goes into considerable detail on HL2.
Apparently, the developers have been working on it since the original HL and have ploughed almost all the money they made into the development of this game (so the developers have been able to do anything they wanted, with no interference from publishers).
The AI is ground breaking (the game is different each time you play it and there are NO scripted scenes), and all the characters have been modeled right down to their musculature.
Each character has a unique personality and details such as lip movements and facial expressions will be totally realistic (just like that nVidia Elf, but better), so even if you are deaf, you'll be able to lip-read the characters.
A full physics system is used so that environments behave as in real life, and the game will be different each time you play - even the characters react to the environment and will behave differently each time.
A full level editor will be supplied with the game, so that you can build your own levels.
I guess that's enough for this installment, but you can always buy a copy of PC Zone if you want to know more.
PS: Anyone that played that Quake 3 demo, will know how lame it was - except for the graphics of course. HL2 has it all, and provides a gaming experience that is more believable than any game yet. It will be unfortunate for other games released after HL2, because they are going to look so bad in comparison.
Oh, and one final thought, now that I've hyped HL2 up so much, you're all guaranteed to be disapointed, and hate it, when it finaly comes out.
