The main quest-line was engaging, the combat was cool, and the puzzle boxes were fun, but I remember being blown away by the size of the world. You could wander for literally hours, exploring new terrain, and discovering additional characters and bonus quest-lines. Its world was expansive and immersive, and it felt alive, like nothing else playable on a 386sx ever had been before.
The next time I felt that sense of aliveness - but better - in a video game was about a decade later, when I took my first Wyvern ride in World of Warcraft, and realized that everything I was seeing below me was really happening. This wasn’t a teleport: if you saw someone fighting something down below you, it was because another player was really fighting something down there. Mind-blowing!