Record your child when they are young... There is some internal biological thing going on. My daughter could wake me up out of a slumber that a freight train running by my pillow would not.
I think even an infant crying would get most people, even if childless.
I put my alarm as birds chirping for a while. The problem was that I couldn't sleep in any longer on weekends, because the birds chirping outside would wake me up.
I used to have a TV which had a setting that would turn it on and go to a specific channel at a set time. I would set it to go to the history channel every morning because they would play random stuff from their archives in the morning, so it was impossible to get fully desensitized. One day I'd wake up to the history of candy, the next day it'd be the history of stealth aircraft, the next day it'd be the history of the klan (that was not the best way to start the day).
A friend of mine had an alarm clock with big rubberized wheels on it that would drive around the room as it went off, so you had to get out of bed to turn it off.
That lasted a few weeks before he grabbed it and chucked it as hard as he could against a wall while still half asleep, then went back to sleep.
a grown man screaming in agony .... (something along the lines of saying something like 'OH GOD, MY LEG, MY LEG, OH GOD, GOD NO, MY LEG!!!!, OH GOD, HELP ME, MY LEG!!)
For a short while when I was having trouble waking up, I used a goat scream (the goat scream) for my alarm. It's close enough to a woman's scream and I gotta say, yes it woke me up, but god, do not do that to yourself.
My theory is that if we split people into two groups - those who hit snooze and those who don’t - and dropped them on a desert island to survive, one group would rebuild civilization while the other descended into chaos and perished.
That's why I always use same ringtone fort both alarm and calls. Sort of programmed my brain to register it as important unless I am exhausted and in deep sleep then nothing wakes me up.
Edit: it's important to note that I almost never snooze. I just set another alarm if I needed few more hours or just power through it.