Probably the only reason I did not get into Terraria as an experienced Minecraft player is that my brain really hates 2D worlds.
I realize I miss out on many wonderful games, but how the hell do you feel comfortable restricted to one plane? This constantly makes me as a character feel I'm out in the open from two sides, and God knows what's there.
Maybe it's some weird quirk, but my brain is strictly 3-dimensional.