Wait, this was all one take? Not spliced together? Some of those falls looked like you had a mm to spare before you would have taken falling damage.

Yes, all one take :-) However there were many trials to get there with less than 20% chance of overall success I would estimate.

e.g. the bit where I hide behind behind a headstone in the graveyard is by no means reliable (maybe 80%?)

Thanks to HN the view count on YouTube has increased dramatically! If it gets past 1000 I'm going to have to record and upload the final section with the combine troops.

EDIT: assuming that is still possible: Valve have made some changes for the twentieth birthday which I noticed today.

e.g. there's more grass and bizarrely the lift button has switched to the other side of the elevator

While you sipping on that coffee, I was crouched down on the same roof surrounded by the awful sound of the incoming sporty zombies. I hate those things, I still do.