I did eventually beat BlackCastle on Masterful but I gave up on the final boss. It's just too long and tedious for me to have the patience for it, especially since each form takes multiple hits and there's like 4 forms and after that you have to do a survive-the clock gauntlet while you're only able to survive 4 hits yourself.
Sometimes I wish I could go back and replay AUS without knowing all the areas. I remember really enjoying the exploration aspect as a kid when I first played it. To think it came out in 2007, I was only 9 at the time... well, I remember the game costing 1 dollar for a while, I think I was a little older than that when I first played it. Maybe like 11 or so. That reminds me of all the times I wanted to play those shareware games on the computer as a kid but my parents refused to pay for anything online back then. I had so many of those free trials of games on my old PC which I think was an old work tower from my uncle's office or something which he gave to me.
In some ways I'm kind of glad my parents never supervised my internet access because while I definitely did visit some stuff I shouldn't have, being exposed to online communities (which can be quite harsh at times) made me a fairly humble person.