I'm flicking through the DMG and have been looking at critical hits, a rule which I think we must have incorporated immediately upon finding out about it. There's been some confusion over the years since I'm sure people have mentioned that AD&D didn't have critical hits but I could always remember using them. The interesting thing though, is that they had a different critical hit as an option.
When rolling a natural 20, you instead get to make a second attack against the same target. If that attack is a natural 20, you can make a 3rd attack (unlikely but could happen). Did anyone use this critical hit rule instead? I don't recall reading it, but then it's been ages since I've really looked through the 2e DMG.