In my honest opinion I think everything so far looks very good with the mod that has been released as media, and I would like to summarize what I would like to see in the mod which are not completly as they are in Half Life 1 but I think would be wicked!
ok small one first, in the Lamda core after you are dodging the lasers at the top of the reactor you come out into a corridor and have to climb up a ladder in an elevator (elevator with a ladder in it wtf) yes it is true, well if my memory serves me correct, could make a nice physics puzzle and I thought some headcrabs jumping out of a vent on you from above at this point would also be good. even an elevator that does not work and then you have to get up into the shaft would be good, with a power failure and lights out momment… But that in my opinion from the original was crap and possibly the only really crap part to the experience that I had.
check it here if you dont believe me
https://www.youtube.com/watch?v=kAexwRmBuI8&feature=related
Next one more involved but would be fairly easy to execute also, I would like to see at least one scientist in a hev suit still alive in xen who is injured and you try to help him by getting water from a healing pool but when you return he is facing away from you when you get closer he turns around and has a headcrab on his head and lashes out at you, and is a bit more tough to kill than a normal zombie… Gonarchs lair would be an ideal setting for this type of small cutscene (helping him is a bluff for the sequence to occur and give hopefullly a little fright to the player)
I only just seen the health chargers from the ps2 version of half life yesterday also and think they look cool with the mechanical arm syringe attachment on them and would like to see this varient in game too.