Cyanosis: You should of made that a little more clear before, otherwise we wouldn't of gone on this little tirade about advancements in AI, but I guess it still made for an interesting conversation nonetheless.
I said it right there in my second response:
Fenixp: Yes, sadly, the more complex the underlying scripting is, the more error prone it becomes. It's a sad reality, but also a testament to how advanced HL's AI actually was. AI in Unreal was not advanced in any meaningful way, it just reacted to player input well. (and it's worth pointing out I actually enjoy the original Unreal more than HL because, amongst other things, yes - AI which directly reacts to you clicking the left mouse button while aiming at it is more challenging that AI which is trying to do its own thing)
I didn't expect this kind of Spanish inquisition! Anyway, obviously, primary prerequisite for me to play a game is that I need to enjoy it. Wolf3D or Dune 2, for instance, are just too primitive for me to enjoy at all. But I still sometimes play Doom because it's just a fun shooter - and I still purposefully don't kill all enemy actors in Half-Life or just passively watch them to see what kind of wacky shit they'll manage to do this time around.