pretty good overhaul of OC, i particularly like the new Vort office that resembles HL1 a lot more
also i appreciate the fact that you merged some of the maps together so that the game doesn't have to load for 30 seconds when i have to go back to fetch the scientists and guards

i also love the callbacks to HL1 as well
(headcrab getting chopped up by a fan blade in the vents,
a wall breaking apart to reveal a hole with a bunch of headcrabs behind it,
the unexpected Vort ambush in the driveway with the bullsquid)

i do have some ideas on how to improve this
(though they're just tiny nitpicks that don't really matter if you add them or not):

1. in the scene where the guard says "We can still climb", a zombie appears from the storage area behind the player.
i think this sequence could be a bit more improved if the zombie was playing dead at first and only wakes up after the guard finishes his dialogue, as it's sort of awkward when the guard is still talking as the zombie is just walking towards him and the scientist

2. in the hole where headcrabs pop out from behind a wall, there's an invisible wall obstructing the player from getting inside the hole.
i think you could remove the invisible wall and add a few supplies in the hole to reward the player for exploration

3. for the "Our Brains And Your Brawn" achievement you now have to bring 1 more scientist who is in the freezer room, and at the end you'll have about 7 NPCs to keep track of to make sure they don't die.
you might wanna add some dialogue at the end room to reassure the players that they DID indeed save everyone (maybe smth like "Thanks for saving all of us Gordon").
this would be useful for players who already have the achievement (like me) and might want to make sure they didn't miss anyone

other than that stuff, this mod is an 8 outta 10 for me!