I had the same experience: I played DS1 almost completely blind (I’d seen my old roommates playing it years ago so I knew some of the tricks, in a half-remembered sort of way). It was hard, and I got stuck in a few places for a really long time but wow it was extremely rewarding. Anyways I’m not that good at videogames, if you’re persistent pretty much anyone can beat dark souls 1 I think
It isn’t stated that they knew it was closed when they arrived. They might have figured it out after the fact.