I forced my way through that cave in Blue/Red that was completely pitch black. I don't know why I didn't get HM Flash (I was a dumb kid). I remember listening intenselywith headphones to the noises that would be made from running into walls, along with counting each press of the d-pad so I could sorta figure out where I was. Still got lost often. I don't know how many poor Zubats I murdered in that cave trying to get through it. Nor do I remember how long it took me to get to the other side.