While this run is technically glitchless, it does exploit a weakness in the cops pathing by placing a sentry gun in a place they usually don't go. They can easily destroy it, but for some reason they usually just stand near it instead of going to a place where they can actually see and shoot the thing. This doesn't mean they can't go there, because there's always a few that do and in many cases the sentry gun is destroyed within minutes. The same thing can be done with a player. Therefore it doesn't technically classify as a glitch.

There was meat in the main room, didn't get an ambush at the start or dozers at the end so it's just like playing on a lower difficulty. The bots never survive that ambush but you can trade them all back in time so that wouldn't matter and you can just run past the four dozers at the escape as they have a small spawn delay.

The strategy I used only really works when the drill breaks late and only once or twice. Ideally it breaks once so you can stay in the kitchen as long as possible. I considered a run failed when the drill broke more than once or if it took more than 5 seconds to get to it. I found that staying in the kitchen for 30 seconds to a minute after the assault started is the most ideal time to get all cops to where you want them, but be in time when the drill breaks. I was a bit late in this run but it still turned out to be fine. The first gas spawn has to be on the yard for obvious reasons, but the second one can be either in the kitchen or the hallway as long as you don't lose too much time getting to the kitchen like I did in this run (attempting to get there in this run would almost definitely have gotten me downed so I bet on the spawn I was at). The sentry gun can be placed in the kitchen too, but then getting the gas there is nearly impossible.

PS: This is what happens when the sentry gun inevitably breaks and here it even held out quite long: