Freedom! Logging in for the first time and knowing nothing about whats happening, and having literally no in-game guidance or objective. It was the ultimate survival, go and do whatever I want.
Ignorance was great, not knowing anything. I didn't use the internet for information about how to do things, instead it was just me and a friend playing on his own single world, exploring and learning and helping each other. I had real fear when I left the safe place I had made for myself. I remember not knowing what happens when I die. Respawn? New World? I got lost in a cave once, and it took me hours to get out. From then on me and my friend decided to put all our torches on one side of the wall, so we can follow them back! I still do it today D:
It was just such a new experience. Minecraft is a well made and immersive game. It was the only non linear game I had even heard of, or played. It was, and to me, still is great.