It had magic item modifiers (damage, hit rating, stat boosts), actual tile based graphics instead of letters like Rogue, and a little bit of a storyline. Still turn-based, random dungeons, classic roguelike features but with a save feature and safe towns with merchants it was more forgiving.
Castle of the Winds is tons of fun, I remember getting part one on an old demo disc and replaying it constantly when I was a kid. Not the most complex or detailed game of its kind, but the sprite work is still fresh in my mind an embarrassing number of years later
I think I did the same thing in college. Kid me had no idea what I was doing. Adult me maxed intelligence and blasted everything that moved with spells.